Suppose the marginal product of the last worker employed by a firm in 40 units of output per day and the daily wage that the firm must pay is $20, while the marginal product of the last machine rented by the firm is 120 units of output per day and the daily rental price of the machine is $30. (a) Why is this firm not maximizing output or minimizing costs in the long run? (b) How can the firm maximize output or minimize costs?