The ratio of boys to girls at a movie is 3:5. If there are 20 girls, how many boys are there?

Answer 1

boys/giirls = 3/5 = x/20

or 3:5 :: x:20

Cross-multiply (or means and extremes):

5x = 60

x = 12

There are 12 boys and 20 girls. 12:20 reduces to 3:5.

Answer 2

3+5=8

X is the total number of boys and girls

5/8 of them are girls and there are 20 girls.

5/8 X = 20

X = 20*8/5 = 160/5 = 32

There are 32 students altogether

20 of them are girls

Then there are 32-20= 12 boys