A bically orginally priced at 225 was marked down 30 % after a week, the bicycle was marked down another 15% off the sale price what are the sale prices of the bike after each discount

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.