The ratio of boy to girls in a class is 3 : 2. There are 15 boys in the class. How many total boys and girls are in the class?

A) 15

B) 23

C) 25

D) 35

3:2 = 15:10 (3x5 = 15 boys; 2x5 = 10 girls)

15+10=25 total boys and girls

answer C) 25

First, let's see what we are told:

1. The ratio of boys to girls is 3:2. Turn that into an equation

2b=3g 2b=3g

2. If two girls are added, the number will be equal

b=g+2 b=g+2

Now, substitute the second equation into the first:

2 (g+2) = 3g 2 (g+2) = 3g

multiply

2g+4=3g 2g+4=3g

subtract 2g

4=g 4=g

So there are 4 girls and, thus 6 boys