How Many Birds?

There are a number of birds on a mango tree also a certain number under the same tree. A bird on the tree says to the ones under, "give us one of your member and we will be double your number". A member of those under the tree replied "give us one of your member and we will be equal your number.

How many birds are there on the tree and how many under the tree?

Answer:

There are 7 birds on the top branch and 5 birds under, If 1 goes from below to above 7+1=8 birds on top and 5-1=4 birds under. If 1 goes to below branch from top 7-1=6 on top and 5+1=6 on below too.