Step 1: Find the time difference in hours or minutes between the local time of the given longitudes and place x.

Step 2: Convert the time difference into longitudes. That is, multiply the number of hours by 15° or divide the number of minutes by 4minutes.

Step 3: Adjust the longitude according to the given time, if local time of place x is ahead of the time at the given longitude then the place is to the East of the longitude if local time is behind the two places in the West so we subtract.

Examples

1) What is the longitude of place x whose local time is 10am, when local time in Tunisia on longitude 10°E is 12noon.

Solution

Step 1: 12-10 = 2hrs

Step 2: 2hrs * 15° = 30°

Step 3: 10°E-30°E = -20° or 20W

2) The local time in Baghdad (Iraq) on longitude 45°E is 3pm. What is the longitude of place x, if its local time is 7pm.

Solution

Step 1: 7pm-3pm = 4hrs

Step 2: 4hrs * 15° = 60°

Step 3: 45°E + 60°E = 105°E