The following equations represent the demand and supply functions in the market for some good where an external cost (negative externality) like pollution results in damages of $4 per unit of the good produced (which means MEC is constant): P = 50 - Q^D MPC = 2 + Q^S Solve for (a) the competitive market equilibrium output and (b) the socially efficient level of output for this market.

Reference

Barry Field and Martha Field (2024), Environmental Economics, 9th Edition, McGraw-Hill.