diff --git a/extra/1-currency-conversion.js b/extra/1-currency-conversion.js
index 75b3c6aab..9f995002a 100644
--- a/extra/1-currency-conversion.js
+++ b/extra/1-currency-conversion.js
@@ -5,7 +5,10 @@
   Write a function that converts a price to USD (exchange rate is 1.4 $ to £)
 */
 
-function convertToUSD() {}
+function convertToUSD(price) {
+  return "$" + price*1.4;
+}
+console.log(convertToUSD(20));
 
 /*
   CURRENCY CONVERSION
@@ -15,16 +18,21 @@ function convertToUSD() {}
   They have also decided that they should add a 1% fee to all foreign transactions, which means you only convert 99% of the £ to BRL.
 */
 
-function convertToBRL() {}
+function convertToBRL(price) {
+  total = price*0.99*5.7;
+  return "BRL" + " "+ total.toFixed(2);
 
-/* ======= TESTS - DO NOT MODIFY ===== 
+}
+console.log(convertToBRL(20));
+
+ ======= TESTS - DO NOT MODIFY ===== 
 There are some Tests in this file that will help you work out if your code is working.
 
 To run the tests for just this one file, type `npm test -- --testPathPattern 1-currency-conversion` into your terminal
 (Reminder: You must have run `npm install` one time before this will work!)
 */
 
-test("convertToUSD function works for £32", () => {
+/*test("convertToUSD function works for £32", () => {
   expect(convertToUSD(32)).toEqual(44.8);
 });
 
diff --git a/extra/2-piping.js b/extra/2-piping.js
index b4f8c4c1b..727b2c6bf 100644
--- a/extra/2-piping.js
+++ b/extra/2-piping.js
@@ -16,26 +16,36 @@
   the final result to the variable goodCode
 */
 
-function add() {
+function add(num1, num2) {
+  return num1 + num2;
 
 }
 
-function multiply() {
+function multiply(num1, num2) {
+  return num1*num2;
 
 }
 
-function format() {
+function format(result) {
+  formatResult = "£" + result
+  return formatResult;
 
 }
 
+
 const startingValue = 2;
+let addResult = add(startingValue, 10);
+let multiplayResult = multiply(addResult, 2)
+let finalResult = format(multiplayResult)
 
-// Why can this code be seen as bad practice? Comment your answer.
-let badCode =
 
+// Why can this code be seen as bad practice? Comment your answer.
+ 
+let badCode = format(multiply(add(startingValue,10),2));
 /* BETTER PRACTICE */
 
-let goodCode =
+let goodCode = finalResult
+console.log(goodCode);
 
 /* ======= TESTS - DO NOT MODIFY ===== 
 There are some Tests in this file that will help you work out if your code is working.
diff --git a/extra/3-magic-8-ball.js b/extra/3-magic-8-ball.js
index 46f65f928..c874ba79f 100644
--- a/extra/3-magic-8-ball.js
+++ b/extra/3-magic-8-ball.js
@@ -45,9 +45,16 @@
 
 // This should log "The ball has shaken!"
 // and return the answer.
+let answerArray
+let randomItem
 function shakeBall() {
   //Write your code in here
+  answerArray = ["It is certin", "it's decideldly so", "As I see it, yes", "Most likely", "Reply hazy, try again", "Ask again later", "Dont count on it", "My replay is no"]
+  let randomIndex = Math.floor(Math.random() * answerArray.length);
+  randomItem = answerArray [randomIndex];
+  console.log(randomItem)
 }
+shakeBall();
 
 /* 
   This function should say whether the answer it is given is
@@ -58,10 +65,40 @@ function shakeBall() {
 
   This function should expect to be called with any value which was returned by the shakeBall function.
 */
-function checkAnswer(answer) {
-  //Write your code in here
+ function checkAnswer(answer) {
+//   //Write your code in here
+switch(randomItem) {
+  case "It is certin":
+    console.log("very postive")
+    break;
+  case "it's decideldly so":
+    console.log("very positive")
+    break;
+  case "As I see it, yes":
+    console.log("positive")
+    break;
+  case "Most likely":
+    console.log("positive")
+    break;
+  case "Reply hazy, try again":
+    console.log("negative")
+    break;
+  case "Ask again later":
+    console.log("negative")
+    break;
+  case "Dont count on it":
+    console.log("very negative")
+    break;
+  case "My replay is no":
+    console.log("very negative")
+    break;
+  
 }
 
+
+ }
+ checkAnswer(randomItem);
+
 /* 
 ==================================
 ======= TESTS - DO NOT MODIFY =====
diff --git a/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index d9e004465..6df0ed926 100644
--- a/mandatory/1-syntax-errors.js
+++ b/mandatory/1-syntax-errors.js
@@ -1,16 +1,16 @@
 // 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 "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 9eb8c8cd7..02461953a 100644
--- a/mandatory/2-logic-error.js
+++ b/mandatory/2-logic-error.js
@@ -1,16 +1,16 @@
 // The syntax for these functions is valid but there are some errors, find them and fix them
 
 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;
+  total = a * b * c;
+  return total;
 }
 
 /* 
diff --git a/mandatory/3-function-output.js b/mandatory/3-function-output.js
index 5a953ba60..0191b8baf 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -1,9 +1,11 @@
 // Add comments to explain what this function does. You're meant to use Google!
+// this function return a random number between 0 and 100.
 function getRandomNumber() {
   return Math.random() * 10;
 }
 
 // Add comments to explain what this function does. You're meant to use Google!
+// the concat() method join 2 strings together.
 function combine2Words(word1, word2) {
   return word1.concat(word2);
 }
@@ -11,6 +13,7 @@ function combine2Words(word1, word2) {
 function concatenate(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.
+  return firstWord.concat(" ", secondWord, " ", thirdWord);
 }
 
 /* 
diff --git a/mandatory/4-tax.js b/mandatory/4-tax.js
index ba77c7ae2..76959c93a 100644
--- a/mandatory/4-tax.js
+++ b/mandatory/4-tax.js
@@ -5,7 +5,11 @@
   Sales tax is 20% of the price of the product.
 */
 
-function calculateSalesTax() {}
+function calculateSalesTax(price) {
+ return price + price*0.2;
+  
+
+}
 
 /*
   CURRENCY FORMATTING
@@ -17,7 +21,13 @@ function calculateSalesTax() {}
   Remember that the prices must include the sales tax (hint: you already wrote a function for this!)
 */
 
-function addTaxAndFormatCurrency() {}
+function addTaxAndFormatCurrency(price) {
+  console.log(price)
+  return "£" + calculateSalesTax(price).toFixed(2);
+  
+}
+console.log(addTaxAndFormatCurrency(40))
+
 
 /* 
 ===================================================