Answer:
24; 12
Step-by-step explanation:
We can set up a system of equations here.
First we can name the number of boys x,
and the number of girls y.
Now we can set up our equations.
x+y=42
and
3/4x+2/3y=30
Now we can set it up for substitution.
x=42-y
We got that by subtracting y from both sides to the first equation
Now we can substitute 42-y in for x in the second equation.
3/4(42-y)+2/3y=30
Distribute.
31.5-3/4y+2/3y=30
Get a common denominator.
31.5-9/12y+8/12y=30
Combine like terms.
31.5-1/12y=30
Subtract 31.5 from both sides.
-1/12y=-1.5
Multiply both sides by -12
y=18
Now we plug that back in.
x+18=42
Subtract 18 from both sides.
x=24
There are 24 boys in the class.
Now 2/3 of girls use the school bus and the total number of girls is 18.
18*2/3=12
12 girls use the school bus.
