Yolanda makes wooden boxes for a craft fair. She makes 200 boxes like the one shown, and she wants to paint all the outside faces

Let x have probability generating function gx (s) and let un generating function u(s) of the sequence uo, u1, satisfies p(x > n). show that the (1- s)u(s) = 1 - gx(s), whenever the series defining these generating functions converge.