VTRMC 2017 Problem 3

Let $ABC$ be a triangle and let $P$ be a point in its interior. Suppose $\angle B A P = 10 ^ { \circ } , \angle A B P = 20 ^ { \circ } , \angle P C A = 30 ^ { \circ }$ and $\angle P A C = 40 ^ { \circ }$ . Find $\angle P B C$ .