Use the purple rectangle (diamond symbols) to shade the area representing the revenue lost from selling fewer units of output. Then use the green ectangle (triangle symbols) to shade the area representing the revenue gained from selling each unit of output at a higher price. 100 90 70 888 T PRICE (Dollars) 60 50 Demand 40 30 20 20 10 0 0 20 40 60 80 100 120 140 160 180 200 QUANTITY (Units) This monopolist's marginal revenue equals $ Revenue Lost Revenue Gained ? (Hint: Enter the negative sign, if necessary.)