Question

suppose you are on 30 degree west and your friend is on 20 degree west find out the time differences between extreme places ?

Answer 1

Longitudinal difference between us:30-20=10 degree (since we're in the same hemisphere)
We know,
For a longitudinal difference of 1 degree , time difference = 4 min
Therefore,
For a longitudinal difference of 10 degree,time difference=4*10 min=40 min.
Therefore time difference between extreme places=40 min=2/3 hr. 

Answer 2

Longitudinal difference between us:30-20=10 degree (since we're in the same hemisphere)We know,For a longitudinal difference of 1 degree , time difference = 4 minTherefore,For a longitudinal difference of 10 degree,time difference=4*10 min=40 min.Therefore time difference between extreme places=40 min=2/3 hr.