diff --git a/exercises/C-variables/exercise.js b/exercises/C-variables/exercise.js
index a6bbb9786..707d2308a 100644
--- a/exercises/C-variables/exercise.js
+++ b/exercises/C-variables/exercise.js
@@ -1,3 +1,5 @@
 // Start by creating a variable `greeting`
-
+let greeting="Hello World";
+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..3772ea23d 100644
--- a/exercises/D-strings/exercise.js
+++ b/exercises/D-strings/exercise.js
@@ -1,3 +1,6 @@
 // Start by creating a variable `message`
+var message = "This is a string";
+var messageType = typeof message;
 
 console.log(message);
+console.log(messageType);
diff --git a/exercises/E-strings-concatenation/exercise.js b/exercises/E-strings-concatenation/exercise.js
index 2cffa6a81..83d66493a 100644
--- a/exercises/E-strings-concatenation/exercise.js
+++ b/exercises/E-strings-concatenation/exercise.js
@@ -1,3 +1,5 @@
 // Start by creating a variable `message`
-
+let fristName="Ahmed ";
+let lastName=" Mohamed";
+message=fristName+lastName;
 console.log(message);
diff --git a/exercises/F-strings-methods/exercise.js b/exercises/F-strings-methods/exercise.js
index 2cffa6a81..d5aff32c0 100644
--- a/exercises/F-strings-methods/exercise.js
+++ b/exercises/F-strings-methods/exercise.js
@@ -1,3 +1,9 @@
 // Start by creating a variable `message`
+let name2="Daniel";
+let message = ` My name is ${name2} and my cheregter numer is  `;
 
-console.log(message);
+let numberCherctor=name2.length;
+console.log(message+numberCherctor);
+
+
+///My name is Daniel and my name is 6 characters long
diff --git a/exercises/F-strings-methods/exercise2.js b/exercises/F-strings-methods/exercise2.js
index b4b46943d..ff8fa15f7 100644
--- a/exercises/F-strings-methods/exercise2.js
+++ b/exercises/F-strings-methods/exercise2.js
@@ -1,3 +1,4 @@
-const name = " Daniel  ";
-
-console.log(message);
+const dname = " Daniel  ";
+let nameof=dname.trim();
+let countCheregter=nameof.length;
+console.log("My name is "+dname+" and my name is "+countCheregter+" characters log");
diff --git a/exercises/G-numbers/exercise.js b/exercises/G-numbers/exercise.js
index 49e7bc00b..623f86863 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=30;
+let  numberOfMentors=15;
+let totalNumberofcyf=numberOfStudents+numberOfMentors;
+console.log("the number of student is "+numberOfStudents+" and the number of montor is "+numberOfMentors+" totel of montor  and studant is "+totalNumberofcyf);
diff --git a/exercises/I-floats/exercise.js b/exercises/I-floats/exercise.js
index a5bbcd852..653e6797c 100644
--- a/exercises/I-floats/exercise.js
+++ b/exercises/I-floats/exercise.js
@@ -1,2 +1,6 @@
 var numberOfStudents = 15;
 var numberOfMentors = 8;
+let studentPerc = Math.round(numberOfMentors / numberOfStudents*100);
+let mentorPerc = Math.abs(studentPerc-100);
+console.log("Percent of student :"+" "+studentPerc+"%");
+console.log("Percent of mentor :" + " " + mentorPerc + "%");
diff --git a/exercises/J-functions/exercise.js b/exercises/J-functions/exercise.js
index 0ae5850e5..e9ba2f0ef 100644
--- a/exercises/J-functions/exercise.js
+++ b/exercises/J-functions/exercise.js
@@ -1,5 +1,6 @@
 function halve(number) {
   // complete the function here
+  return number/2;
 }
 
 var result = halve(12);
diff --git a/exercises/J-functions/exercise2.js b/exercises/J-functions/exercise2.js
index 82ef5e780..6d216ffc6 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..50b7e50ca 100644
--- a/exercises/K-functions-parameters/exercise.js
+++ b/exercises/K-functions-parameters/exercise.js
@@ -1,5 +1,6 @@
 // Complete the function so that it takes input parameters
-function multiply() {
+function multiply(a,b) {
+  return a*b;
   // Calculate the result of the function and return it
 }
 
diff --git a/exercises/K-functions-parameters/exercise2.js b/exercises/K-functions-parameters/exercise2.js
index db7a8904b..e366146b2 100644
--- a/exercises/K-functions-parameters/exercise2.js
+++ b/exercises/K-functions-parameters/exercise2.js
@@ -1,5 +1,7 @@
 // Declare your function first
-
+function divide(a,b){
+    return a/b;
+}
 var result = divide(3, 4);
 
 console.log(result);
diff --git a/exercises/K-functions-parameters/exercise3.js b/exercises/K-functions-parameters/exercise3.js
index 537e9f4ec..994e80e9b 100644
--- a/exercises/K-functions-parameters/exercise3.js
+++ b/exercises/K-functions-parameters/exercise3.js
@@ -1,5 +1,8 @@
 // Write your function here
-
+function createGreeting(a)
+{
+    return "Hello, my name is "+a;
+}
 var greeting = createGreeting("Daniel");
 
 console.log(greeting);
diff --git a/exercises/K-functions-parameters/exercise4.js b/exercises/K-functions-parameters/exercise4.js
index 7ab44589e..1ed807457 100644
--- a/exercises/K-functions-parameters/exercise4.js
+++ b/exercises/K-functions-parameters/exercise4.js
@@ -1,5 +1,8 @@
 // Declare your function first
 
 // Call the function and assign to a variable `sum`
-
+function addnumber(a,b){
+    return a+b;
+}
+let sum=addnumber(13,124)
 console.log(sum);
diff --git a/exercises/K-functions-parameters/exercise5.js b/exercises/K-functions-parameters/exercise5.js
index 7c5bcd605..c35eee5d8 100644
--- a/exercises/K-functions-parameters/exercise5.js
+++ b/exercises/K-functions-parameters/exercise5.js
@@ -1,5 +1,8 @@
 // Declare your function here
-
+function createLongGreeting(name,age){
+    // console.log(`Hello, my $[name] is  and I'm $[age]  years old`);
+    return "Hello, my name is " + name+" i'm "+age+"years old";
+}
 const greeting = createLongGreeting("Daniel", 30);
 
 console.log(greeting);
diff --git a/exercises/L-functions-nested/exercise.js b/exercises/L-functions-nested/exercise.js
index a5d377442..5884683a7 100644
--- a/exercises/L-functions-nested/exercise.js
+++ b/exercises/L-functions-nested/exercise.js
@@ -3,3 +3,11 @@ var mentor2 = "Irina";
 var mentor3 = "Mimi";
 var mentor4 = "Rob";
 var mentor5 = "Yohannes";
+function hello(a){
+    return "Hello "+a;
+}
+console.log(hello(mentor1));
+console.log(hello(mentor2));
+console.log(hello(mentor3));
+console.log(hello(mentor4));
+console.log(hello(mentor5));
diff --git a/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index a10cc9ac2..58784066f 100644
--- a/mandatory/1-syntax-errors.js
+++ b/mandatory/1-syntax-errors.js
@@ -1,18 +1,18 @@
 // There are syntax errors in this code - can you fix it to pass the tests?
 
-function addNumbers(a b c) {
-  return 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 getTotal(a, b) {
-  total = a ++ b;
-
-  return "The total is total";
+{
+  return "Hello, my name is"+ " " + name +" "+ "and I am" +" "+ age + " "+"years old";
 }
+function getTotal(a,b) {
+ let  total = a + b;
 
+  return "The total is"+" "+ total;
+}
 /* 
 ===================================================
 ======= TESTS - DO NOT MODIFY BELOW THIS LINE =====
diff --git a/mandatory/2-logic-error.js b/mandatory/2-logic-error.js
index 9cca7603b..0ed4c2254 100644
--- a/mandatory/2-logic-error.js
+++ b/mandatory/2-logic-error.js
@@ -1,16 +1,19 @@
 // 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();
+word = "  CodeYourFuture  ";
+word = " CodeYourFuture teaches coding     ";
+function getStringLength (word) {
+ return word.length;
 }
-
+word = getStringLength("A wild sentence appeared!");
+word = getStringLength("Turtle"); ;
 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..970b54a5c 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!
+
 function getRandomNumber() {
+  // we use Random  method to get a random number after that multplie this number 10 
   return Math.random() * 10;
 }
 
 // Add comments to explain what this function does. You're meant to use Google!
+
 function combine2Words(word1, word2) {
+  //The concat() method joins two or more strings.
   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..c86f7c19a 100644
--- a/mandatory/4-tax.js
+++ b/mandatory/4-tax.js
@@ -5,7 +5,10 @@
   Sales tax is 20% of the price of the product.
 */
 
-function calculateSalesTax() {}
+function calculateSalesTax(price) {
+  let salesTax=(price*20)/100;
+return price+salesTax;
+}
 
 /*
   CURRENCY FORMATTING
@@ -17,7 +20,9 @@ function calculateSalesTax() {}
   Remember that the prices must include the sales tax (hint: you already wrote a function for this!)
 */
 
-function addTaxAndFormatCurrency() {}
+function addTaxAndFormatCurrency(tax) {
+  return "£"+calculateSalesTax(tax).toFixed(2);
+}
 
 /* 
 ===================================================