Jeremy's father drives him to school in rush hour traffic in 20 minutes. one day there is no traffic, so his father can drive him 18 miles per hour faster and gets him to school in 12 minutes. how far in miles is it to school?

(need shown work for review)

9

Step-by-step explanation:

Let's make the speed of the dad's driving in rush hour x miles per minute. (I'm just doing miles per minute because it uses minutes.)

Then, when there's no traffic, it's x miles per minute+18 miles per hour=x miles per minute+0.3 miles per minute(18/60).

So basically, we've got this:

x miles per minute=20min

x+0.3 miles per minute=12min

Now, using the formula, d(distance)=t(time)*s(speed), I'm going to find x.

d=20x=12(x+0.3)=12x+3.6

As you can see here, 8x=3.6. Therefore, x=0.45. Now, back to the formula. d=20x. Since you know what x is, this is easy. d=9