Birds in Trees Puzzle - Solution

The Puzzle:

Birds in Trees
There are 2 trees in a garden (tree "A" and "B") and on the both trees are some birds.

The birds of tree A say to the birds of tree B that if one of you comes to our tree, then our population will be the double of yours.

Then the birds of tree B tell to the birds of tree A that if one of you comes here, then our population will be equal to that of yours.

Now answer: How many birds in each tree?

Our Solution:

The solution is 7 and 5.

7 on tree A, and 5 on tree B
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