diff --git a/.DS_Store b/.DS_Store
new file mode 100644
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Binary files /dev/null and b/.DS_Store differ
diff --git a/exercises/.DS_Store b/exercises/.DS_Store
new file mode 100644
index 000000000..6c0a231fe
Binary files /dev/null and b/exercises/.DS_Store differ
diff --git a/exercises/B-hello-world/exercise.js b/exercises/B-hello-world/exercise.js
index b179ee953..463580493 100644
--- a/exercises/B-hello-world/exercise.js
+++ b/exercises/B-hello-world/exercise.js
@@ -1 +1 @@
-console.log("Hello world");
+console.log("Hayaaa");
diff --git a/exercises/C-variables/exercise.js b/exercises/C-variables/exercise.js
index a6bbb9786..505ca719e 100644
--- a/exercises/C-variables/exercise.js
+++ b/exercises/C-variables/exercise.js
@@ -1,3 +1,7 @@
 // Start by creating a variable `greeting`
-
+let greeting= "hello";
+console.log(greeting);
+console.log(greeting);
 console.log(greeting);
+
+
diff --git a/exercises/D-strings/exercise.js b/exercises/D-strings/exercise.js
index 2cffa6a81..dab8ecd57 100644
--- a/exercises/D-strings/exercise.js
+++ b/exercises/D-strings/exercise.js
@@ -1,3 +1,3 @@
 // Start by creating a variable `message`
-
-console.log(message);
+let message = "";
+console.log(typeof message);
diff --git a/exercises/E-strings-concatenation/exercise.js b/exercises/E-strings-concatenation/exercise.js
index 2cffa6a81..b4a627a1f 100644
--- a/exercises/E-strings-concatenation/exercise.js
+++ b/exercises/E-strings-concatenation/exercise.js
@@ -1,3 +1,6 @@
 // Start by creating a variable `message`
+let greeting = "Hello, my name is ";
+let firstName ="Maira";
+let fullGreeting = greeting + firstName;
+console.log(fullGreeting);
 
-console.log(message);
diff --git a/exercises/F-strings-methods/exercise.js b/exercises/F-strings-methods/exercise.js
index 2cffa6a81..888e8bf6e 100644
--- a/exercises/F-strings-methods/exercise.js
+++ b/exercises/F-strings-methods/exercise.js
@@ -1,3 +1,6 @@
 // Start by creating a variable `message`
+let firstName = "Maira";
+let nameLength = firstName.length
 
+let message = "My name is " + firstName + " and my name is 5 characters long"
 console.log(message);
diff --git a/exercises/F-strings-methods/exercise2.js b/exercises/F-strings-methods/exercise2.js
index b4b46943d..63b389edd 100644
--- a/exercises/F-strings-methods/exercise2.js
+++ b/exercises/F-strings-methods/exercise2.js
@@ -1,3 +1,7 @@
 const name = " Daniel  ";
 
-console.log(message);
+let message = "My name is " + firstName + " and my name is 5 characters long";
+let result = message.trim();
+console.log(result);
+// let text = "       Hello World!        ";
+// let result = text.trim();
\ No newline at end of file
diff --git a/exercises/G-numbers/exercise.js b/exercises/G-numbers/exercise.js
index 49e7bc00b..cf84a42ee 100644
--- a/exercises/G-numbers/exercise.js
+++ b/exercises/G-numbers/exercise.js
@@ -1 +1,5 @@
 // Start by creating a variables `numberOfStudents` and `numberOfMentors`
+let numberOfStudents = 50;
+let numberOfMentors = 20;
+let result = numberOfStudents + numberOfMentors;
+console.log(result);
\ No newline at end of file
diff --git a/exercises/I-floats/exercise.js b/exercises/I-floats/exercise.js
index a5bbcd852..4057c69e9 100644
--- a/exercises/I-floats/exercise.js
+++ b/exercises/I-floats/exercise.js
@@ -1,2 +1,14 @@
 var numberOfStudents = 15;
 var numberOfMentors = 8;
+let total = numberOfStudents + numberOfMentors;
+let percentageOfStudents = numberOfStudents * 100/ total;
+let newPercentageOfStudents= Math.round(percentageOfStudents);
+console.log(newPercentageOfStudents);
+let percentageOfMentors = numberOfMentors * 100/ total;
+let newPercentageOfMentors = Math.round(percentageOfMentors);
+console.log(newPercentageOfMentors);
+
+
+
+// var preciseAge = 30.612437;
+// var roughAge = Math.round(preciseAge); 
\ No newline at end of file
diff --git a/exercises/J-functions/exercise.js b/exercises/J-functions/exercise.js
index 0ae5850e5..1baf74dff 100644
--- a/exercises/J-functions/exercise.js
+++ b/exercises/J-functions/exercise.js
@@ -1,7 +1,16 @@
 function halve(number) {
   // complete the function here
+  return number/2;
 }
 
 var result = halve(12);
 
 console.log(result);
+
+
+// function double(number) {
+//   return number * 2;
+// }
+// var result = double(2);
+
+// console.log(result); // 4
diff --git a/exercises/J-functions/exercise2.js b/exercises/J-functions/exercise2.js
index 82ef5e780..468d45596 100644
--- a/exercises/J-functions/exercise2.js
+++ b/exercises/J-functions/exercise2.js
@@ -1,5 +1,6 @@
 function triple(number) {
   // complete function here
+  return number * 3;
 }
 
 var result = triple(12);
diff --git a/exercises/K-functions-parameters/exercise.js b/exercises/K-functions-parameters/exercise.js
index 8d5db5e69..64d94062b 100644
--- a/exercises/K-functions-parameters/exercise.js
+++ b/exercises/K-functions-parameters/exercise.js
@@ -1,6 +1,9 @@
+
+
 // Complete the function so that it takes input parameters
-function multiply() {
+function multiply(a , b) {
   // Calculate the result of the function and return it
+  return a *b;
 }
 
 // Assign the result of calling the function the variable `result`
diff --git a/exercises/K-functions-parameters/exercise2.js b/exercises/K-functions-parameters/exercise2.js
index db7a8904b..6a3372166 100644
--- a/exercises/K-functions-parameters/exercise2.js
+++ b/exercises/K-functions-parameters/exercise2.js
@@ -1,4 +1,7 @@
 // Declare your function first
+function divide (a,b){
+    return a /b;
+}
 
 var result = divide(3, 4);
 
diff --git a/exercises/K-functions-parameters/exercise3.js b/exercises/K-functions-parameters/exercise3.js
index 537e9f4ec..8004a821a 100644
--- a/exercises/K-functions-parameters/exercise3.js
+++ b/exercises/K-functions-parameters/exercise3.js
@@ -1,5 +1,20 @@
 // Write your function here
 
-var greeting = createGreeting("Daniel");
+function createGreeting (){
+    let name = "Daniel"
+    let message = "hello my name is  " + name;
+return message
+}
+
+var greeting = createGreeting("Maira");
 
 console.log(greeting);
+
+// let userName = 'John';
+
+// function showMessage() {
+//   let message = 'Hello, ' + userName;
+//   alert(message);
+// }
+
+// showMessage(); // Hello, John
diff --git a/exercises/K-functions-parameters/exercise4.js b/exercises/K-functions-parameters/exercise4.js
index 7ab44589e..3a57f9294 100644
--- a/exercises/K-functions-parameters/exercise4.js
+++ b/exercises/K-functions-parameters/exercise4.js
@@ -1,5 +1,10 @@
 // Declare your function first
-
+// - Write a function that adds two numbers together
+// - Call the function, passing `13` and `124` as parameters, and assigning the returned value to a variable `sum`
 // Call the function and assign to a variable `sum`
-
+let num1 = 13;
+let num2 = 124;
+function addNum (num1, num2){
+    return num1+ num2;
+}
 console.log(sum);
diff --git a/exercises/K-functions-parameters/exercise5.js b/exercises/K-functions-parameters/exercise5.js
index 7c5bcd605..517e5248b 100644
--- a/exercises/K-functions-parameters/exercise5.js
+++ b/exercises/K-functions-parameters/exercise5.js
@@ -1,5 +1,10 @@
 // Declare your function here
-
-const greeting = createLongGreeting("Daniel", 30);
-
+// Write a function that takes a name (a string) and an age (a number) and returns a greeting (a string)
+// const greeting = createLongGreeting("Daniel", 30);
+function createLongGreeting(name, age){
+    
+    return `Hello, my name is ${name} and I'm ${age} years old`;
+}
+let greeting = createLongGreeting("Daniel", 30);
+// let greeting = createLongGreeting("Maira", 32);
 console.log(greeting);
diff --git a/exercises/L-functions-nested/exercise.js b/exercises/L-functions-nested/exercise.js
index a5d377442..f433bfd20 100644
--- a/exercises/L-functions-nested/exercise.js
+++ b/exercises/L-functions-nested/exercise.js
@@ -3,3 +3,16 @@ var mentor2 = "Irina";
 var mentor3 = "Mimi";
 var mentor4 = "Rob";
 var mentor5 = "Yohannes";
+
+function toUpperCase(name){
+    return name.toUpperCase();
+}
+function sayHello(mentor){
+    let upperLetter = toUpperCase(mentor);
+    return `HELLO ${upperLetter}`;
+}
+console.log(sayHello(mentor1));
+console.log(sayHello(mentor2));
+console.log(sayHello(mentor3));
+console.log(sayHello(mentor4));
+console.log(sayHello(mentor5));
diff --git a/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index a10cc9ac2..d7fd088b7 100644
--- a/mandatory/1-syntax-errors.js
+++ b/mandatory/1-syntax-errors.js
@@ -1,16 +1,24 @@
 // There are syntax errors in this code - can you fix it to pass the tests?
 
-function addNumbers(a b c) {
+function addNumbers(a ,b ,c) {
+  
   return a + b + c;
+  
 }
 
-function introduceMe(name, age)
-  return "Hello, my name is " + name "and I am " age + "years old";
+
+function introduceMe(name, age) {
+  return "Hello, my name is " + name + " and I am " + age + " years old";
+}
+
+ 
+
+
 
 function getTotal(a, b) {
-  total = a ++ b;
+  total = a + b;
 
-  return "The total is total";
+  return "The total is " + total;
 }
 
 /* 
diff --git a/mandatory/2-logic-error.js b/mandatory/2-logic-error.js
index 9cca7603b..28cda425d 100644
--- a/mandatory/2-logic-error.js
+++ b/mandatory/2-logic-error.js
@@ -1,16 +1,16 @@
 // The syntax for this function is valid but it has an error, find it and fix it.
 
 function trimWord(word) {
-  return wordtrim();
+  return word.trim();
 }
 
 function getStringLength(word) {
-  return "word".length();
+  return word.length;
 }
 
 function multiply(a, b, c) {
-  a * b * c;
-  return;
+  
+  return a * b * c ;
 }
 
 /* 
diff --git a/mandatory/3-function-output.js b/mandatory/3-function-output.js
index 5a953ba60..d92156ec5 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -1,14 +1,19 @@
 // Add comments to explain what this function does. You're meant to use Google!
+
+// This function getting random number between 0(inclusive) and 1 (inclusive)  sourse https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/random
 function getRandomNumber() {
   return Math.random() * 10;
 }
 
 // Add comments to explain what this function does. You're meant to use Google!
+
+// this function combining 2 words by using concat method sourse https://www.w3schools.com/jsref/tryit.asp?filename=tryjsref_concat_string1
 function combine2Words(word1, word2) {
   return word1.concat(word2);
 }
 
 function concatenate(firstWord, secondWord, thirdWord) {
+  return firstWord + " " + secondWord + " " + thirdWord;
   // Write the body of this function to concatenate three words together.
   // Look at the test case below to understand what this function is expected to return.
 }
diff --git a/mandatory/4-tax.js b/mandatory/4-tax.js
index ba77c7ae2..68c9626bf 100644
--- a/mandatory/4-tax.js
+++ b/mandatory/4-tax.js
@@ -5,8 +5,17 @@
   Sales tax is 20% of the price of the product.
 */
 
-function calculateSalesTax() {}
-
+function calculateSalesTax(price) {
+  let totalPrice = price * 0.2 + price;
+  return totalPrice;
+}
+let totalPrice = calculateSalesTax(15);
+console.log(totalPrice);
+let totalPrice2 = calculateSalesTax(17.50);
+console.log(totalPrice2);
+let totalPrice3 = calculateSalesTax(34);
+console.log(totalPrice3);
+ 
 /*
   CURRENCY FORMATTING
   ===================
@@ -16,8 +25,20 @@ function calculateSalesTax() {}
 
   Remember that the prices must include the sales tax (hint: you already wrote a function for this!)
 */
+// Компания сообщила вам, что цены должны иметь 2 десятичных знака.
+//    Они также должны начинаться с символа валюты.
+//    Напишите функцию, которая добавляет налог к числу, а затем преобразует итоговую сумму в формат 0,00 фунтов стерлингов.
 
-function addTaxAndFormatCurrency() {}
+//    Помните, что цены должны включать налог с продаж (подсказка: вы уже написали для этого функцию!)
+function addTaxAndFormatCurrency(number) {
+  // let addTax = number + totalPrice;
+  // return `£${addTax}`;
+  let result = `£${calculateSalesTax(number).toFixed(2) }`;
+  return result
+}
+console.log( addTaxAndFormatCurrency(15) )
+console.log( addTaxAndFormatCurrency(17.50) )
+console.log( addTaxAndFormatCurrency(34) )
 
 /* 
 ===================================================