Question

in a group of 48 children there are three times as many boys as girls. how many girls are there

Answer 1

if x=girls,
then we have 3x boys.

We know that all children are boys+girls, so x+3x, which is 4x and 4x is 48, so one x is 12.

So there are 12 girls and 36 boys.

Answer 2

There are x girls in the group.
There are three times as many boys as girls, so the number of boys is 3x.
There are 48 children in the group.

$x+3x=48 \\ 4x=48 \\ x=\frac{48}{4} \\ x=12$

There are 12 girls in the group.