Fix replaceAll syntax and calculate percentage change

Author: lauracs24

Sprint-1/3-mandatory-interpret/1-percentage-change.js

@@ -2,21 +2,43 @@ let carPrice = "10,000";
 let priceAfterOneYear = "8,543";
 
 carPrice = Number(carPrice.replaceAll(",", ""));
-priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
 
 const priceDifference = carPrice - priceAfterOneYear;
 const percentageChange = (priceDifference / carPrice) * 100;
 
 console.log(`The percentage change is ${percentageChange}`);
 
-// Read the code and then answer the questions below
-
 // a) How many function calls are there in this file? Write down all the lines where a function call is made
+// Function calls are when we use () like: something()
+// Line 4: carPrice.replaceAll(",", "")
+// Line 4: Number(...)
+// Line 5: priceAfterOneYear.replaceAll(",", "")
+// Line 5: Number(...)
+// Line 10: console.log(...)
+// Answer: 5 function calls
 
 // b) Run the code and identify the line where the error is coming from - why is this error occurring? How can you fix this problem?
+// The error comes from the console.log line because it uses single quotes with ${percentageChange}
+// ${...} only works inside backticks `...` (template strings)
+// Fix: use backticks: console.log(`The percentage change is ${percentageChange}`);
 
 // c) Identify all the lines that are variable reassignment statements
+// Reassignment means we change an existing variable's value (no let/const on the line)
+// Line 4: carPrice = Number(carPrice.replaceAll(",", ""));
+// Line 5: priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
+// Answer: lines 4 and 5
 
 // d) Identify all the lines that are variable declarations
+// Declarations use let or const
+// Line 1: let carPrice = "10,000";
+// Line 2: let priceAfterOneYear = "8,543";
+// Line 7: const priceDifference = carPrice - priceAfterOneYear;
+// Line 8: const percentageChange = (priceDifference / carPrice) * 100;
+// Answer: lines 1, 2, 7 and 8
+
+// e) Describe what the expression Number(carPrice.replaceAll(",", "")) is doing - what is the purpose of this expression?
+// replaceAll(",", "") removes commas from the string (e.g. "10,000" becomes "10000")
+// Number(...) converts the cleaned string into a real number so we can do maths with it
+// Purpose: turn "10,000" (text) into 10000 (number)
 
-// e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?