Suppose a firm with a production function given by q=18k^0.8 l^0.2 produces 800 units of output. the firm pays a wage of $20 per unit and pays a rental rate of capital of $30 per unit. a. compute the optimal number of units of labor and capital that the firm should employ to minimize the cost of production (for 800 units of output). b. compute the total cost. c. determine the short run and long run costs of increasing output to 2000 units