Can someone help i dont know any of these formulas

Weak battery is considered to be a part of routine a. inspection b. wear and tear c. maintenance d. check

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.

As a salesperson you get $23/ day and $3.60/each sale you make. if you want to make at least $84. in one day, how many sales would need to make? a 15b 16c 17d 18