Two cars, A and B, travel along interstate 20 from Atlanta to Dallas. Car A left Atlanta at 10 PM traveling at a constant speed of 60 mph. Car B left the same point in Atlanta 30 minutes later traveling at a constant speed of 80 mph. In how many minutes will Car B overtake Car A if neither car stops at any exit or experiences traffic (and thus both cars maintain their constant speeds)?	Choose one
A) 90  B) 95  C) 100  D) 110  E) 120
We need to use a form of D=RT [distance=rate*time]   Car 90 will have travelled 30 minutes longer than car B when they meet, so   Car 90 travel time: T+.5 (use 1/2 hour since the rates are in hours)   Car B travel time: T   Car 90 rate: 60 mph   Car B rate: 80 mph   Car 90 distance = Car B distance   so   (R car 90)*(T car 90) = (R car B)*(T car B)   60*(T+.5) = 80*T   60T + 30 = 80T   30 = 20T   1.5 = T   1.5 hours = 90 minutes   90
<result>A</result>
Two cars, A and B, travel along interstate 20 from Atlanta to Dallas. Car A left Atlanta at 10 PM traveling at a constant speed of 60 mph. Car B left the same point in Atlanta 30 minutes later traveling at a constant speed of 80 mph. In how many minutes will Car B overtake Car A if neither car stops at any exit or experiences traffic (and thus both cars maintain their constant speeds)?