Question

2/3 of a class are girls.

a) What is the ratio girls to boys in the class?
b) What is the ratio boys to girls in the class?

Answer 1

a) 2:3
b) 1:3
2/3 of the class are girls, so 2:3. That leaves 1/3 of the class as boys, so 1:3 ratio.

Answer 2

1/3 of the class are boys