Question

The ratio of girls to boys who participated in the quiz bowl was 7:5. There were 42 girls in the competition. How many boys participated? A) 28 B) 30 C) 35 D) 49

Answer 1

The way i do it, is sort of like this :

Is 7 a factor of 42? 
  Is 5 a factor of 42? 

7 is a factor of 42. 
It must be in multiples of 7!

Therefore, we have 5 on the other side, which makes it 5 x 7 = 35