In a group of 30 children, there are 4 times as many boys as girls. How many girls are there?

X=mumber of boys

y=number of girls.

I suggest this system of equations:

x+y=30

x=4y

We can solve this system of equations by susbtitution method.

4y+y=30

5y=30

y=30/5=6

x=4y

x=4*6=24

Answer: there are 6 girls