Two trains leave a station traveling the same direction. Train A leaves the station traveling at a constant speed of 60 mph, and train B leaves the station traveling at a constant speed of 80 mph. If both trains maintain constant speeds, in how many minutes will train B overtake train A if train A left 40 minutes prior to train B?  Options:
A) 90  B) 100  C) 110  D) 120  E) 130
We can use 120=RT [distance=rate*time]   Train A will have traveled for 40 minutes longer than train B when B overtakes A, so   time of train A: T+40minutes = T+(2/3) hours (use hours since the rate is in hours)   time of train B: T   rate of train A: 60 mph   rate of train B: 80 mph   the distances traveled by each will be equal when train B overtakes train A, so we can set the right sides of 120=RT equal for the two trains   (rate of train A)*(time of train A) = (rate of train B)*(time of train B)   60*(T+2/3)=80*T   60T + 40 = 80T   40 = 20T   2 = T   2 hours = 120 minutes   120
<result>D</result>
Two trains leave a station traveling the same direction. Train A leaves the station traveling at a constant speed of 60 mph, and train B leaves the station traveling at a constant speed of 80 mph. If both trains maintain constant speeds, in how many minutes will train B overtake train A if train A left 40 minutes prior to train B?