The ratio of the number of girls to the number of boys in a class is 6:7 . If three are 21 boys in the class, then the number of girls in the class is

Explanation:

Let the number of girls in the class be x

Number of boys in the class = 21

Ratio of number of girls to the number of boys is 6:7

Therefore;

6:7 = x:21

6/7 = x/21

7x = 126

x = 126/7

x = 18

Therefore, the number of girls in the class are 18.

Final answer: Hence, we concluded that the number of girls in the class are i.e. Option c