The following table shows the demand for a product produced by a monopolist, who has a constant marginal cost and an average total cost of $45 per unit. Quantity (thousands of units) 0 1 2 3 4 5 6 Price (dollars per unit) 120 105 90 75 60 45 30 a. Calculate total revenue and marginal revenue for level of quantity. b. What are the profit-maximizing output level and price level? In no more than three sentences, explain why. c. Calculate the monopolist's profit. d. Calculate the Lerner Index for this industry.