) A firm uses labor and machines to produce output according to the production function , where L is the number of units of labor used and M is the number of machines. The cost of labor is $40 per unit and the cost of using a machine is $10. MPL is and MPK is . a. How many units of labor and how many machines would the firm use to produce 40 units in the cheapest possible way? b. How much would this cost?