Question

then three are 20 birds in each tree是什么意思

英语翻译
A group of birds fly into the woods.If only one bird stays in each tree.there are three birds that have no trees to stay in.If each tree has three birds in it,there trees are left with no birds in.
How many trees are there in all?
Answer:( )

Answer 1

一群鸟飞进树林.如果每棵树上只有一只鸟,那么有三只鸟没有地方可待.如果每棵树上有三只鸟,那么还会剩下三棵树没有鸟在上面.总共有几棵树?
回答：6棵树.