A 1939 Ford heads out of town traveling at 40 mph. Three hours later a 1957 Chevy follows traveling at 70 mph. How long will it take for the Chevy to overtake the Ford?

4 hours

using the formula

distance = speed * time (t)

the Ford will have travelled 3 * 40 = 120 miles before the Chevy leaves

the Ford's distance can be modelled as

distance = 40t + 120

the Chevy's distance can be modelled as

distance = 70t

equating the right sides and solve for t

70 t = 40t + 120 (subtract 40t from both sides)

30t = 120 (divide both sides by 30)

t = 4

the Chevy catches up with the Ford after 4 hours