Indian Standard Time (IST) is ahead of Greenwich Mean Time (GMT) by how much time?

Indian Standard Time (IST) is ahead of Greenwich Mean Time (GMT) by:

How much is the difference between Indian Standard Time (I.S.T.) and Greenwich Mean Time (G.M.T.)?

A place lies 90° east of Greenwich. How much ahead is its local time?

The time at Cairo is 2 hours ahead of Greenwich. Hence, it is located at-

What is the Standard Meridian line of India?