diff --git a/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index d9e004465..ff863d202 100644
--- a/mandatory/1-syntax-errors.js
+++ b/mandatory/1-syntax-errors.js
@@ -1,16 +1,19 @@
 // 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`;
+let name = "Sonjide";
+let age = 27;
+function introduceMe(name, age){
+  return `Hello, my name is ${name} and I am ${age} years old`;
+}
+
 
+let a = 23;
+let b = 5;
 function getTotal(a, b) {
-  total = a ++ b;
-
-  return "The total is total";
+  return `The total is ${total = a + b}`;
 }
 
 /* 
diff --git a/mandatory/2-logic-error.js b/mandatory/2-logic-error.js
index 9eb8c8cd7..6a1dc9592 100644
--- a/mandatory/2-logic-error.js
+++ b/mandatory/2-logic-error.js
@@ -1,19 +1,22 @@
 // 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;
+  return  a * b * c;
 }
 
-/* 
+
+/*
 ===================================================
 ======= TESTS - DO NOT MODIFY BELOW THIS LINE =====
 
@@ -29,9 +32,7 @@ test("trimWord trims leading and trailing whitespace", () => {
 });
 
 test("trimWord doesn't remove whitespace in the middle of the string", () => {
-  expect(trimWord(" CodeYourFuture teaches coding     ")).toEqual(
-    "CodeYourFuture teaches coding"
-  );
+  expect(trimWord(" CodeYourFuture teaches coding     ")).toEqual("CodeYourFuture teaches coding");
 });
 
 test("getStringLength returns the length of a word", () => {
diff --git a/mandatory/3-function-output.js b/mandatory/3-function-output.js
index 5a953ba60..580adf257 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -1,17 +1,27 @@
 // Add comments to explain what this function does. You're meant to use Google!
+
 function getRandomNumber() {
   return Math.random() * 10;
 }
+/* Generates a random number. As the values generated are between 0 and 1 we need to multiply by 10 to get a whole number between 1 and 10. */
+
 
 // Add comments to explain what this function does. You're meant to use Google!
 function combine2Words(word1, word2) {
   return word1.concat(word2);
 }
+/* The concat() method concatenates (joins) two or more strings. It returns a new array, containing the joined strings. */
+
 
+let firstWord = "I";
+let secondWord = "am";
+let thirdWord = 13;
 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);
 }
+console.log(concatenate);
+
+
 
 /* 
 ===================================================
diff --git a/mandatory/4-tax.js b/mandatory/4-tax.js
index ba77c7ae2..c0bbcd5b7 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(product) {
+  let salesTax = (product * 20) / 100;
+  return priceTotal = product + salesTax;
+}
+
 
 /*
   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(product) {
+  let salesTax = (product * 20) / 100;
+  let priceTotal = product + salesTax
+  
+  return `£${priceTotal.toFixed(2)}`;
+}
 
 /* 
 ===================================================
diff --git a/package.json b/package.json
index 93e0861e3..9e7f2ffeb 100644
--- a/package.json
+++ b/package.json
@@ -14,15 +14,21 @@
     "url": "https://github.com/CodeYourFuture/JavaScript-Core-1-Coursework-Week1/issues"
   },
   "jest": {
-    "setupFilesAfterEnv": ["jest-extended"],
+    "setupFilesAfterEnv": [
+      "jest-extended"
+    ],
     "projects": [
       {
         "displayName": "mandatory",
-        "testMatch": ["<rootDir>/mandatory/*.js"]
+        "testMatch": [
+          "<rootDir>/mandatory/*.js"
+        ]
       },
       {
         "displayName": "extra",
-        "testMatch": ["<rootDir>/extra/*.js"]
+        "testMatch": [
+          "<rootDir>/extra/*.js"
+        ]
       }
     ]
   },