Question

I have this problem that I cant solve I need your help. There's 4 multiple choice answers at the bottom, its one of those.

Answer 1

4/7 are girls
9 are boys
total=boys+girls=4/7+boys
boys=9
total=7/7
7/7=4/7+boys
subtract 4/7 from both sides
3/7=boys
therefor
3/7 of class=9
multily oth sides by 7/3 to clear fraction
class=63/3=21
class=21
answe ris C 21

Answer 2

To solve this problem, first we need to figure out what fraction of the class are boys.  

If we know that 4/7 of the students are girls, there are only 3/7 students left in the class, therefore they must be boys.

We know that there are 9 boys in the class.  (Let the variable x represent how many students total there are in the class.)

3/7x=9

If we divide both sides by 3/7, we get 

x=21.

Therefore, there are 21 students in the class.  Your answer is C. 21.