A competitive manufacturer of gadgets has the following production function: Q = 20K - K2 + 30L - 2L2 . The price of gadgets, p = 1; the wage rate, w = 10; the rental price of capital, r = 16. (a) What is the profit-maximizing level of output? (b) At this equilibrium, what is marginal cost? (c) At this equilibrium, what is the level of profits? (d) At this equilibrium, what is the marginal rate of technical substitution?