Answers (1)
The world is divided into 24 time zones of 15 degrees each. The 0 degree point is arbitrarily set at Greenwich, England and that is why you hear of GMT, Greenwich Mean Time. You can click on the clock in your computer, select "Set Time And Date", and see the time anywhere in the world in hours before or after GMT.
3:00 PM at 30° east would be 1:00 PM GMT and 30° west would be 11:00 AM.