At country concert, the ratio of the number of boys to the number of girls is 2:7. If there are 250 more girls than boys, how many boys were at the concert?

Answer 1

2/9 boys b
7/9 girls g
b = (2/7) g or g = (7/2) b

g - 250 = b
(7/2) b - b = 250

(5/2) b = 250

5 b = 500

b = 100