A Day at the Appliance Store

Difficulty: Hard · Topics: Discrete Mathematics, Sets, Word Problems

A store sells only refrigerators, washing machines and dishwashers. In one day 71 people shopped there.

16 of them bought a refrigerator and a washing machine, and 43 of them bought a refrigerator and a dishwasher. Nobody bought only a refrigerator, and everyone who bought a washing machine and a dishwasher also bought a refrigerator.

If 21 people bought only a washing machine or only a dishwasher, how many people in total bought both a washing machine and a dishwasher?