Final answer:
The difference in longitude between point P (50°W) and point Q (150°W) is calculated by subtracting the longitude of point P from point Q, resulting in a difference of 100°.
Step-by-step explanation:
The difference in longitude between point P (latitude 50°N, longitude 50°W) and point Q (latitude 50°N, longitude 150°W) is the absolute value of the difference between the two longitudes. To calculate this, you subtract the longitude of point P from the longitude of point Q: 150°W - 50°W = 100°. Therefore, the difference in longitude between P and Q is 100°.