两棵树上共有麻雀24只，第一棵树飞到第二棵树上5只，又从第二棵树上飞走7只到第一棵树，这时第一棵树上的麻雀的只数是第二棵的2倍。原来每棵树上各有几只？

本来题目中鸟是25只，可惜这是一道错题，只好把25改成24了。解答如下：

24÷（1+2）＝8（只）……第二棵现在

8×2＝16（只）……第一棵现在

8+7-5＝10（只）……第二棵原来

16-7+5＝14（只）……第一棵原来

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