So the ratio of boys to girls is 12:24.. now, is that an equivalent ratio as 2 boys for 4 girls? or 2:4? let's see.

you could start simplifying the 12/24 fraction by dividing by some common multiple, say 2, and get 6/12, then divide by 3 and get 2/4 and stop there.
then you'll notice that 12/24 is really 2/4 in disguise.
In this problem, we need to plug in the given x values for

and find a and b.
When we plug in 1, we get:

Simplify:



We got our first statement about the values of the variables. If we find one more we can find those 2 variables.
We have another given root: 4.
Plug it in:




Now we have our second one. We can combine them:

I use elimination method which is easier here.
Multiply the top equation by -1:

Add them up:

Simplify:

Now we have a, we can plug in one of those equations to find b:



So, the answers are

and

.
4 times because if you count 10, 20, 30, 40, so it has to be 4
The answer should be $8 if you are trying to find the unit rate. All you have to do is divide 32 by 4 and you get 8. Hope that helped.