Find the average rate of each train.

Question

A freight train takes 16 hours to travel the same distance that an express train travels in 12 hours. The average rate of the train is 15 miles per hour more than that of the freight train. Find the average rate of each train. 

Answer 1

d=r*t

d=r*16  (freight)

d=(r+15)*12  (express)

equate the two equations because the distances are the same

16r=12(r+15)

16r=12r+180

16r-12r=180

4r=180

r=180/4

r=45 mph for the freight train

r+15=45+15=60 mph for the express train