Elementary school math problem: two brothers went fishing and caught 27 pieces. If an elder brother gives his younger brother four dollars, his elder brother is twice as big as his younger brother. How many pieces did the two brothers catch? Solution: Suppose my brother catches X fish, then my brother catches (27-x) fish.

2×(x-4)=(27-x)+4。

Solution: x=22

27-22=5

A: My brother caught 22 fish and my brother caught 5.