Solve these riddles

There were 30 cows in a field, 28 chickens, how many didn't?

Two potato chips were sitting on the empire state building, one jumped off, why didn't the other?

Respuesta :

1st:
It's like this: 30 cows in a field, 20 ate chickens, how many didnt?
28=(20 ate)
30-20="10"