If total revenue received from the sale of x items is given by R(x) = 10 In (4x + 1), while the total cost to produce x items is C(x) = - (a) The marginal revenue (b) The profit function P(x) (c) The marginal profit when x = 40 (d) Interpret the results of part (c). (a) How can the marginal revenue be found? A. Find R(x)-C(x). B. Find the derivative of R(x). C. Find the derivative of R(x) - C(x). OD. Find R Find R (2) X find the following.