30 Cows, 28 Chickens
Riddle: There are 30 cows in a field, and 28 chickens. How many didn't?
Answer: 10. Listen closely: 30 cows and twenty-eight chickens. Say EIGHT and ATE. They sound the same. Therefore, it means 20 ATE chickens. 30-20=10, so 10 cows didn't eat any chickens.
Source: https://www.riddles.com/5132
