Question 28 (1 point) Market demand is given as QD = 220 - 3P. Market supply is given as QS = 3P + 40. Each identical firm has MC = 0.3Q and ATC = 0.2Q. What is a firm's average total cost? O $30 O $20 O $18 O $5Question 39 (1 point) Figure 10-4 Price Social Cost Private Cost PA P1 Po Demand Quantity Q1 Qo Refer to Figure 10-4. Which price and quantity combination represents the social optimum? OO PO and Q1 P2 and Q1 P2 and Q0