A small trader buys something at one price and sells it at another. Three of the four amounts (buying price, selling price, number sold, total profit or loss) are given, and the student finds the fourth.
Working backwards from the total is the point: total = (selling price − buying price) × number sold. Every division comes out exactly.
Numbers&Me is free. Sign up to practise more, or set it as homework in under a minute, and it marks itself.