Question

Calculate the time on longitude 30 degree west when it is 11 am at place x which is located at longitude 80° East​

Answer 1

Difference of 90-degrees . . . . . given that 360-degrees corresponds to 24-hours (15-degrees per hour), 90-degrees will correspond to 90/15 = 6-hours time difference

So 11:00Am at 30-degrees east will correspond to 11 - 6 = 5:00AM at 60-degrees west (Sun rises in east and sets in the west)