Hi!
Make use of vector addition - by making use of the fact that the net change in the ##x##-direction is independent of the change in the ##y##-direction.
Before you attempt to draw the vectors, you need to figure out the values of bx and cy because you don't know how big they are and whether they are positive or negative. Do you know how to answer parts (a) and (b) without drawing a vector diagram? @LemmeThink gave you a hint.