Learn to write code by shipping code that gets reviewed line by line.

// submission 04 / cart-total.js41const TAX_RATE = 0.2;42const round = (n) => Math.round(n * 100) / 100;43 44export function cartTotal(items) {45  let total = 0;46  for (const item of items) {47-   total += item.price;47+   total += item.price * item.qty;48  }49-   return total;49+   return round(total * (1 + TAX_RATE));50}

1. 01 / line 47

   The loop added one unit per line, so a basket of three charged for one. Quantity now multiplies the unit price before it joins the total.

2. 02 / line 49

   Tax sits at the return boundary, not inside the loop. One place to change the rate when it moves.

3. 03 / line 49

   Rounding runs once, at the end. Earlier drafts rounded per row and drifted by a few kopiykas on large orders.