Statistics not in formula booklet

Question 1

7. PGF: If Y=aX+b, the probability generating function Gy(t) =

Answer 1

Gy(t) = t^bGx(t^a)

Question 2

7. PGF: If Z=Y+X, Gz(t) =

Answer 2

Gz(t) = Gy(t)*Gx(t)