I am confused as to how to graph without standard Demand and Supply equations; how do I set up the main equations to be able to answer the question?

A firm can invest X units improving the quality of water, at a cost, c(x) = x2. For simplicity we assume a perfectly competitive market in the supply of clean water, so the market price is: p = MC = 2x. The economy consists of two consumers, Angus and Beatrice, who benefit from clean water. Angus derives a private benefit, bA(x) = x(200 - x), from have having a clean source of water. Beatrice benefits bB (x) = x(100 - x). They each know each other's valuation of clean water. MPBA = 200 - 2x MPBB = 100 - 2x a) What is the Marginal Social Cost (MSC) and the Marginal Social Benefit (MSB) of consuming clean water, x? b) Draw a graph indicating the Marginal Cost (MSC), Marginal Private Benefit for Angus and Beatrice (MPBA and MPBB), and the Marginal Social Benefit (MSB). c) What is the socially most efficient level of investment, x*? d) In a private market economy, how much investment in clean water, x4 , does Angus purchase? e Beatrice anticipates that Angus will purchase x4. How much of the public good, x, will Beatrice purchase? f) How much is produced in the private market equilibrium? How much is purchased by Beatrice, and how much is purchased by Angus