posted by Kirsten on .
Train A leaves a station traveling at 80km/h. Two hours later, train B leaves the same direction at 90km/h. How long does it take train B to catch up to train A?
They will have traveled the same distance, but the difference is their times will be 2 hours
time for slower train = D/80
time for faster train = D/90
D/80 - D/90 = 2
9D - 8D = 1440
D = 1440
Time for train B (the faster) = 1440/90 = 16 hrs.
in 16 hrs, the faster train goes 16(90) = 1440
in 18 hrs, the slower train goes 18(80) = 1440