Car A and car B start at the same spot. Car A leaves 20 minutes before car B and is traveling at 70 mph. Car B is traveling at 80 mph. How long does it take for car B to catch up to car A?

Answer 1

20 minutes = 1/3 hour

70 ( t+ 1/3) = 80t

70t + 70/3 = 80t

70/3 = 10t

7/3 = t

80 * 7/3 = 560/3 = 186 and 2/3

70 * (7/3 + 1/3) = 70 * 8/3 = 560/3

the answer is 7/3 hours = 2 and 1/3 hours