If 30% of a class consists of girls and there are 21 boys in the class then how many girls are there in the class

Question

If 30% of a class consist of girls and there are 21 boys in the class ,then how many girls are there in the class

Answer 1

If 30% are girls, then 70% are boys.

 

c represents the number in the class

0.70c = 21

c = 30

 

0.30(30) = 9