Two trains leave the station at the same time, one heading East and the other heading West. The westbound train is going 60mph. The eastbound train is going 80mph. How long will it take the two trains to be 252 miles apart?
The space between them is growing at the rate of (60 + 80) = 140 miles per hour. It will be 252 miles long in 252/140 = 1.8 hours. That's 1 hour 48 minutes.
