One automobile starts out from a town at 8 a.m. and travels at an average speed rate of 60mph. 2 hours later, a second automobile starts out to overtake the first. If the second automobile travels at an average rate of 80mph, how long will it travel before it overtakes the first?
First auto has a 2 x 60 = 120 mile headstart
Closing speed of the second auto is 80 - 60 = 20 m/hr it will take 120 m / 20 m /hr = 6 hours to catch the first auto