At a school event, there were 96 girls. The ratio of the number of girls to the number of boys was 4 : 5. After some time, some boys arrived and the ratio became 2 : 3.

What is the unit rate?

How many boys arrived?

1 - Before the boys arrived, the ratio of girls to boys was: 96 / B = 4/5, solve for B

B = 120 boys.

2 - After few more boys arrived, the ratio of girls to boys: 96 / B = 2 / 3, solve for B

B = 144 boys.

3 - 144 - 120 = 24 boys arrived.

4 - The unit ratio is 96:144 == 1: 1.5