If there are 20 girls and 15 boys in a class, the ratio of number of girls to the number of boys is

3 : 4

4 : 3

2 : 1

5 : 3

⇒ Number of girls = 20

⇒ Number of boys = 15

The ratio of girls to boys: ⇒ Girls: Boys = 20:15

⇒ Girls: Boys = 20 ÷ 5: 15 ÷ 5 ⇒ Girls: Boys = 4:3