Distance, Rate and Time

Question

Two trains leave towns 909 km apart at the same time and travel toward each other. One train travels 15 km/h faster than the other. If they meet in 3 hours, what is the rate of each train?

Answer 1

if r is the rate of the slower train, then r+15 is the rate of the faster train. The combined speed is (2r+15). Think why we add them them. The total time is 3 hrs and the total distance is 909km.

r*t=d, so (2r+15)*3 = 909. Then 2r+15 =303, then 2r =288, so r = 144 and r+15=159