In a family there are several brothers and sisters. Every 2 boys have brothers as many as sisters and each girl has 2 brothers less than twice as many brothers as sisters. Now find the number of boys and girls.

Explanation:-

Let B be the number of brothers and S be the number of sisters in the family.
Consider any two boys. They would be having (B - 2) brothers (excluding the two). But this number is equal to the number of sisters they have.
Therefore,
B - 2 = S
or , B - S = 2 ............(1) Each girl will have (S - 1) sisters. Twice the number of sisters = 2(S - 1).
Since, each girl has twice as many brothers as sisters, we have, 2(S-1)-2 = B
2S - 4 = B ........... (2)

Substituting, eqn (2) in Eqn (1), we get
2S - 4 - S = 2
S = 6
On substituting S = 6 in eqn (1) , we get
B - 6 = 2
B = 8.