What is the time and day at a certain place on 60°w longitude when it is 5:30 am on friday at a place 90 ° E longitude ?

Answer 1

The angle between is 150°
which is 150/360 or 5/12 of a rotation.
5/12 of 24 hours is 10 hours.

so the time would be 5:30 - 5:00 = 19:30 ---> evening of previous day
( that would be 7:30 pm using US notation)
time decreases from east to west

Answer 2

Hard