Respuesta :
There are 30 boys in the competition. You can find it by first dividing 42 by 7 which is 6, then you multiply 6 by 5 to get 30.
Alright! To answer this, you need to cross multiply. Before doing that, set up your ratios
7:5
42: x
7x= (5x42)
7x= 210
x= 210 / 7
x= 30 boys
7:5
42: x
7x= (5x42)
7x= 210
x= 210 / 7
x= 30 boys