A train goes twice as fast downhill as it can go uphill, and 2/3 as fast uphill as it can go on level ground. If it goes 120 mph downhill, how long will it take to travel 45 miles on flat land?

Answer 1

speed uphill=120/2=60
speed level=3/2 * uphill=90
speed downhill=120

on flat land, d=45=90*t
t=1/2 hr