Respuesta :

TSO
Boys are b
Girls are g

b + g = 120
2g = b

Substitute the second equation into the first

2g + g = 120
3g = 120
g = 40

Plug in g = 40 and solve for b

b + g = 40
b + 40 = 120
b = 80

There are 40 girls and 80 boys.