3. [-/5 Points] DETAILS TANAPMATH7 9.8.009. Williams Commuter Air Service realizes a monthly revenue represented by the following function, where R(x) is measured in dollars and the price charged per passenger is x dollars. R(x) = 4,400x - 110x (a) Find the marginal revenue R'(x). R' (x ) = (b) Compute the following values. R'(19) = R'(20) = R'(21) = (c) Based on the results of part (b), what price (in dollars) should the airline charge in order to maximize their revenue? $ MY NOT