Final answer:
To arrive at one terminal at 9:10 AM, the train should leave the other terminal at 7:50 AM, after subtracting the round trip time of 1 hour and 20 minutes from the arrival time.
Step-by-step explanation:
To find out at what time the train should leave the other terminal to arrive at one terminal at 9:10 AM, we need to subtract the round trip time from the arrival time. Given that the round trip time is 1 hour 20 minutes, we can calculate the departure time by subtracting 1 hour and 20 minutes from 9:10 AM.
9:10 AM is the same as 8 hours and 70 minutes, so we subtract 1 hour and 20 minutes from that:
- 8 hours 70 minutes
- - 1 hour 20 minutes
- = 7 hours 50 minutes
Therefore, the train should leave the other terminal at 7:50 AM to be back by 9:10 AM.