A New Hampshire textile mill releases pollution into nearby wetlands, and the associated health and ecological damages are not considered in the private market. Suppose you are an environmental economist working with the following marginal benefits and costs for this market, where Q is thousands of pounds and P is price per pound. 

MPB = 800 – 0.5Q

MPC = 20 + 0.3Q

MEB = 0

MEC = 0.4Q

a. Find the competitive equilibrium, Q_C and P_C, and the efficient equilibrium, Q_E and P_E.

b. Suppose the textile mill owned the rights to the wetlands, and it is negotiating with a private environmental group that is willing to pay the mill to produce less output. For the 800^th unit of output, determine the range within which a payment would be acceptable to both parties.