I think this is a fairly easy one. So if someone would give me any hint to the solution to this problem, then I can carry on.

Problem 1:

The bearing of B from A is 70 degrees North of East; the bearing of C from B is 60 degrees South of East and the bearing of A from C is 20 degrees South of West. If AB is 10 meters, find the length of BC.

Thank you very much guys !!