5.3.2 Greenwich Mean Time [GMT] and Time Zones
• Greenwich Mean Time (GMT) is a term originally referring to mean solar time at the Royal Observatory in Greenwich, London. It is commonly used in practice to refer to Coordinated Universal Time (UTC).
The starting point for the time zone is at 0 and is located a Mt the Greenwich Meridian,in london ,England .
TIME DIFFERENCE
WHEN SIGN ARE THE SAME
whether both + or - then SUBTRACT
WHEN SIGN ARE NOT THE SAME
whether both + or - then ADD