Atool set is on sale for $424.15the original price of the tool set was 499.00 what percent of the original price is the sale price

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.