Open our example file. Make sure you're signed in to Google, then click File > Make a copy.
Select the Challenge sheet.
In cell D4, create a formula that would calculate how much the customer would save on each item by multiplying the unit price, quantity, and discount shown in cell E2.
Use the fill handle to copy the formula you created in step 3 to cells D5:D12.
When you're finished, your spreadsheet should look something like this: