Hi Carmen.
You can find the solution if you identify
 What you are trying to find
 What you know
 How the different quantities are related to each other.
Let's do that with your question:
 You want to find the distance, so let's call it D.
 You know that if Cary goes 60 mph, he gets there 1 hour early AND if he goes 30 mph, he gets there 1 hour late. So if he goes 30 mph, he gets there 2 hours later than if he goes 60 mph.
 Distance = speed x time. Let's write this as D = ST where T will be the time it takes him to get there if he goes 60 mph.
Now you fill in the relationship(s) in part 3 with the values in part 2:
D = 60T
and
D = 30(T+2)
Because he goes the same distance D, but the time is 2 hours more than the time for the faster speed.
So now you have two equations with two unknown values  only one of which you really care about. To solve this, you need to eliminate the other variable (T). There are several ways of doing this, but I often find the easiest way is to solve both equations for the variable you don't care about first:
D = 60T therefore T = D/60,
and
D = 30(T+2) therefore D = 30T + 60
therefore
T = D/30  2
Now remember that when two things equal a third thing, then the first two things have to equal each other, so
T = D/60 and T = D/30  2
means
D/60 = D/30  2
and the rest I'll leave to you.
Hope this explanation helps,
Stephen La Rocque.
