To determine the local time at a specific longitude, you need to consider the time difference from Greenwich Mean Time (GMT) and convert it to the local time zone.
Since each time zone covers approximately 15 degrees of longitude, you can calculate the time difference by dividing the longitude by 15. In this case, 80 degrees west longitude divided by 15 gives us approximately 5.33 time zones to the west of GMT.
Since we are assuming GMT at 12 noon, we can calculate the local time by subtracting 5 hours (5 time zones) from 12 noon.
12 noon - 5 hours = 7:00 AM
Therefore, at 80 degrees west longitude, the local time would be approximately 7:00 AM.