The production function Q = KL + M has marginal products MPK = L, MPL = K,

Question:

The production function Q = KL + M has marginal products MPK = L, MPL = K, and MPM = 1. The input prices of K, L, and M are 4, 16, and 1, respectively. The firm is operating in the short run, with K fixed at 20 units and M fixed at 40. What is the short-run total cost of producing 400 units of output?