diff --git a/extra/1-currency-conversion.js b/extra/1-currency-conversion.js
index 75b3c6aab..88b567a97 100644
--- a/extra/1-currency-conversion.js
+++ b/extra/1-currency-conversion.js
@@ -5,7 +5,12 @@
   Write a function that converts a price to USD (exchange rate is 1.4 $ to £)
 */
 
-function convertToUSD() {}
+function convertToUSD(price) {
+  let gbpToUSD = 1.4;
+  let totalPrice = (price * gbpToUSD);
+  return totalPrice; 
+}
+convertToUSD(32)
 
 /*
   CURRENCY CONVERSION
@@ -15,7 +20,14 @@ 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(brazilianPrice) {
+  let gbpToBrl = 5.643;
+  let totalFee = (brazilianPrice * gbpToBrl);
+  return totalFee;
+}
+
+convertToBRL(30)
+convertToBRL(1.5)
 
 /* ======= 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/2-piping.js b/extra/2-piping.js
index b4f8c4c1b..e155bec3f 100644
--- a/extra/2-piping.js
+++ b/extra/2-piping.js
@@ -16,13 +16,19 @@
   the final result to the variable goodCode
 */
 
-function add() {
-
+function add(number1, number2) {
+  return number1 + number2;
 }
+add(1, 4)
+add(2.4, 5)
 
-function multiply() {
-
+function multiply(num1, num2) {
+  return num1 * num2;
+  
 }
+multiply(2, 3)
+multiply(4, 4)
+
 
 function format() {
 
diff --git a/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index d9e004465..e651523e3 100644
--- a/mandatory/1-syntax-errors.js
+++ b/mandatory/1-syntax-errors.js
@@ -1,18 +1,22 @@
 // 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 "and I am $age years old`;
+function introduceMe(name, age){
+  return ("Hello, my name is Sonjide and I am 27 years old");
+
+}
 
 function getTotal(a, b) {
-  total = a ++ b;
+  total = (a + b);
 
-  return "The total is total";
+  return "The total is " + total;
 }
-
+addNumbers(3, 4, 6);
+introduceMe("Sonjide", 27);
+getTotal(23, 5);
 /* 
 ===================================================
 ======= TESTS - DO NOT MODIFY BELOW THIS LINE =====
diff --git a/mandatory/2-logic-error.js b/mandatory/2-logic-error.js
index 9eb8c8cd7..253cff5e5 100644
--- a/mandatory/2-logic-error.js
+++ b/mandatory/2-logic-error.js
@@ -9,10 +9,11 @@ function getStringLength(word) {
 }
 
 function multiply(a, b, c) {
-  a * b * c;
-  return;
+  return (a * b * c);
+  
 }
-
+multiply(2,3,6);
+multiply(2,3,4);
 /* 
 ===================================================
 ======= TESTS - DO NOT MODIFY BELOW THIS LINE =====
diff --git a/mandatory/3-function-output.js b/mandatory/3-function-output.js
index 5a953ba60..491eff3c4 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!
+// A function called getRandomNumber and it returns a random integer from 0 to 9
 function getRandomNumber() {
   return Math.random() * 10;
 }
 
 // Add comments to explain what this function does. You're meant to use Google!
+// A function called combine2Words that takes in two arguments word1 and word2 and returns a new string which is a concatenation of the two arguments.
 function combine2Words(word1, word2) {
   return word1.concat(word2);
 }
@@ -11,6 +13,11 @@ 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.
+  // let twoWords = firstWord.concat(secondWord);
+  // let finalAnswer = twoWords.concat(thirdWord);
+  let finalAnswer = `${firstWord} ${secondWord} ${thirdWord}`;
+  return finalAnswer;
+
 }
 
 /* 
diff --git a/mandatory/4-tax.js b/mandatory/4-tax.js
index ba77c7ae2..927b11de1 100644
--- a/mandatory/4-tax.js
+++ b/mandatory/4-tax.js
@@ -5,7 +5,12 @@
   Sales tax is 20% of the price of the product.
 */
 
-function calculateSalesTax() {}
+function calculateSalesTax(price) {
+  return (price * 1.2);
+}
+calculateSalesTax(15);
+calculateSalesTax(17.50);
+calculateSalesTax(34);
 
 /*
   CURRENCY FORMATTING
@@ -17,7 +22,13 @@ function calculateSalesTax() {}
   Remember that the prices must include the sales tax (hint: you already wrote a function for this!)
 */
 
-function addTaxAndFormatCurrency() {}
+function addTaxAndFormatCurrency(number, calculateSalesTax) {
+  let total = (number + calculateSalesTax);
+  return "£" + total.toFixed(2);
+  
+}
+// addTaxAndFormatCurrency(15, calculateSalesTax);
+
 
 /* 
 ===================================================