1, Blackie caught 10 fish and Xiaobai caught 3 fish, so how many fish did they catch?

A: 10+3= 13.

They caught 13 fish in one breath.

2. Blackie caught 10 fish and Xiaobai caught 3, so how many more fish did Blackie catch than Xiaobai?

A: 10-3=7.

Xiaohei caught seven more fish than Xiaobai.