10. Suppose that r(x) = 9x and c(x)=x3-6x2 + 5x represent the revenue and cost function, respectively, where x represents thousands of units. The production level that maximize profit = ____

9„ A store can sell 20 bicycles per week at a price $400. each. The manager estimates that for each $10 price reduction she can sell two more bicycles per week. The bicycles cost the store $200 each. Find the price of the bicycles and quantity that maximize profit?____