I have some money. I spend half at the bookshop, a quarter at the supermarket and an eighth on sweets. I have £3.25 left. How much money did I have to start with?

Answer 1

You spent 1/2 + 1/4 + 1/8 or 7/8 of your money
leaving you with 1/8 of your money
1/8 x = 3.25
so you had x = 3.25/(1/8) = £ 26