At a country concerts the ratio of the number of boys to the number of girls 2 to 7.if there are 250 more girls than boys how many boys are at the concerts.

Let B be the number of boys and G= number of girls:

B/G = 2/7 (given)

And

G= 250+B (given), then

B/G = B/(250+B) = 2/7

B/(250+B) = 2/7 → Cross multiplication:

7.B = 2(250+B) → 7.B = 500 + 2.B

5.B = 500  And B = 500/5   And B = 100

Boys = 100  and Girls = 350

Proof: 100/350 = 10/35 = 2/7