posted by Cecilia .
Your flight takes off from the eastern United States at 10 AM. What time will you arrive on the west coast, if the flight takes six hours?
When it's 10 AM in the Eastern zone, it's 7 AM on the west coast.
One way to figure it is to understand that the flight leaves at 7 AM Pacific time. Add 6 to 7 to find out what time it arrives.