Birds in Trees Puzzle
There are 2 trees in a garden (tree "A" and "B") and in 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 double yours.
Then the birds of tree B tell the birds of tree A that if one of you comes here, then our population will be equal to yours.
How many birds in each tree?