I am having problems setting this equation up The problem is

I am having problems setting this equation up. The problem is: If two cars leave the same location at the same time, And car one is traveling 20 MPH faster than car two in opposite directions, and they are 168 miles apart 1 1/2 hours later...how fast is each one going?

Solution

Assume the speed of car one is x mph,
then the speed of car two is x-2 mph.
When they travel in the opposite direction,
distance = sum of two speed * Time,
So, 168 = (x+x-2)* (3/2) = 3x -3,
or 3x = 171, x = 57 and x-2 = 55.
Answer: speed of car 1 is 57 MPH,
speed of car 2 is 55 MPH