There are 160 boys.
Set up a proportion:
the ratio of girls to boys is 7/8, we don’t know how many boys there are but we know that there are 140 girls.
7/8 = 140/x
Make sure that girls and girls are across from each other in the proportion. 7 should be across from 140. 8 is across from x. X represents how many boys there are.
Solve for X (the amount of boys) and you get 160 boys.
And you can always check your answer by plugging it back into the problem.
