There are two branches in a tree. The birds were talking with each other. The birds on top said to the birds down, "if one of you will come up we will double your numbers down" and the birds down responded back, "if one of you will come down our numbers will be even."
Question: How many birds are there on the upper branch and how many birds are there on the lower branch?
Answer: 7 birds on top and 5 birds below branch.