Write an expression for the eighth partial sum of the series using summation notation

Given f(x)= 9x+1 and g(x)=x^3, choose the expression (f*g)(x)

Mozart lenses inc. recently introduced seelites, a thinner lens for eyelasses. of a sample of 800 eyeglass wearers, 246 said they would purchases their next pair of eyeglasses with the new lenses. lenses inc. estimates that the number of people who purchase eyeglasses in a year is 1,700,000. most eyeglasses wearer buy one new pair of eyeglasses a year. what is the annual sales potential for the new lenses.

I'm confused on this could anyone me and show me what i need to do to solve it.