Solving a distance rate time word problem

Question

Two cars leave towns 540 kilometers apart at the same time and travel toward each other. One car's rate is 20 kilometers per hour less than the other's. If they meet in 3 hours, what is the rate of the slower car? Do not do any rounding.

Answer 1

distance=rate*time

540=r*3+(r-20)*3

540=3r+3r-60

540+60=6r

600=6r

r=600/6

r=100 kph

r-20=100-20=80 kph (answer)