Final answer:
To determine the longitude based on different time zones, calculate the difference in time, which corresponds to the longitude difference.
Step-by-step explanation:
The question asks about determining longitude based on different time zones. When it is 5 am in the student's location and 7:30 pm GMT, we can calculate the difference in time to determine the longitude. Since each time zone is 15 degrees wide, the difference in time corresponds to the longitude difference. For example, if the student's location is ahead by 14.5 hours (which is 22.5 degrees), then the longitude would be 22.5 degrees east.