In a particular competitive market, the industry’s private marginal cost at output level Q ≥ 0 is PMC(Q) = 1 (in $ per unit) when Q ≤ 11 and PMC(Q) = 2Q − 11 when Q > 11. The height of the demand curve for the industry’s output is 7 − (Q/3) when the quantity demanded is Q ≤ 21. Draw the supply and demand curves and find the competitive equilibrium price and quantity traded when there is no tax. Show all your work and explain all your steps.