Suppose the demand for a chemical is given by Q=100-3P, where quantity is measured in pounds. The market supply is given by MC = 6. Assume the social marginal cost of this product is $8 per unit. a. Find the competitive equilibrium and the level of marginal profit at that point? b. Find the efficient equilibrium and the level of marginal profit at that point? Is it different from the external cost? Give an intuitive explanation.