Write out the answer. 这是一道应用题，请列式解答，并写出答语。 Three cats are hungry. The yellow cat wants to eat twenty-one little fish. The white cat wants to eat twenty

little fish. The black cat wants to eat thirty-one little fish. How much fish do they want to eat?

1. 列式解答：

2. 写出答语：

试题答案

1. 21+20+31=72
2. They want to eat seventy fish.