In Problem, total revenue is in dollars and x is the number of units.

Suppose that demand for local cable TV service is given by

p = 120 - 0.4x

where p is the monthly price per subscriber in dollars and x is the number of subscribers (in hundreds).

(a) Find the total revenue as a function of the number of subscribers (in hundreds).

(b) Find the number of subscribers when the company charges $80 per month for cable service. Then find the total revenue for p = $80.

(c) How could the company attract more subscribers?

(d) Find and interpret the marginal revenue when the price is $80 per month. What does this suggest about the monthly charge to subscribers?