Problem 4 (Competitive equilibrium) Consider a market with 40 identical consumers whose quasilinear utility from consuming an amount :10 of a good and an amount m of \"money\" is given by U (3:, m) = 2J5 + m. There are identical suppliers in perfect competition with cost function C(q) = (12/2. 1. Derive the aggregate demand function. 2. Determine the competitive equilibrium. 3. Show in a diagramme that the competitive equilibrium maximises welfare