An oil tanker sails from a port P to port Q, 20km away and on a bearing of 110 degrees from P. After reaching Q, it sets sail to R, 15 km away and on a bearing of 150 degrees from Q. It then proceeds to sail to S, a port 20 km away and on a bearing of 050 degrees from R. Draw a sketch to indicate the relative positions of the ports P, Q, R and S. Calculate

a) how far south of P is S

b) how far east of P is S

c) the bearing of S from P.