Frank started out in his car travelling 45 mph. When Frank was 1/3 miles away, Daniel started out from the same point at 50 mph to catch up with Frank. How long will it take Daniel to catch up with Frank
Let the time when Daniel catches up with Frank =T (hours)
50T - 45T = 1/3, solve for T
T =1 / 15 of an hour. Or: 1/15 x 60 =4 minutes - when Daniel will catch up with Frank.