Hi, for this question, when it asks about overtaking, I put 150 cause that was the only option where one would be ahead of the other car. Wouldn’t 120 minutes = cars are side by side? or does overtake mean they’re beside each other and not ahead …
For this question, it is important to recognize that Car A is traveling 60 mph and Car B is traveling 80 mph in the same direction. Since the cars are moving in the same direction, then we subtract the smaller speed from the larger speed. The new speed is r = 80 mph - 60 mph = 20 mph. Since B is 40 miles behind A, then d = 40 mi.
Since r = 20 mph and d = 40 mi, then from the equation d = rt, we get that 40 mi = (20 mph)t → t = 2 hours. Since 2 hours = 120 mins, then the answer is 120 min.
When they say “overtake”, they mean the instant when they are beside each other.
I hope this helps.