In diagram below, N is the North Pole and S is the South Pole. The location of point P is (40o S, 70o W) and POQ is the diameter of the earth.
Find the longitude of Q.
Since PQ is a diameter of the earth and the longitude of P is θo W, the longitude of Q is (180o – θo) E.
Longitude of P = 70o W
Longitude of Q = (180o – 70o) E
= 110o E