But with subtracting integers
The new rules are, every time you want to buy something, you have to pick up an integer problem card. If you answer the card right you may buy it, if not you have to wait to try again your turn. If you land on a free parking you have to pick up and integer problem card, same rules apply if you answer the problem right you get the free parking money, if not then better luck next time. Those are the new rules.