Car A and Car B are traveling at 45 mph and 60 mphrespective

Car A and Car B are traveling at 45 mph and 60 mph,respectively.If Car A leaves a depot 40 minutes earlier than Car B,how long will it take Car B to overtake Car A if they both follow the same route?

overtake speed is 15 mph
car A is 30 miles ahead
t=D/r
t=30/15
t=2 hrs