A monopolist has a cost function, 𝐶(𝑥) = 30𝑥 and a demand curve given by

𝐷(𝑝) = 1000 − 15𝑝.
1.4.1 Derive expressions for marginal cost (MC) and marginal revenue (MR) .
1.4.2 How much will the monopolist charge and how many units of output will it produce?
1.4.3 What is the socially efficient quantity (the quantity that maximises total surplus)?