Consider the demand and supply equations for world coal market, Qd= 7875000 - 2850P Qs = 2400P Where P is price per tonne. Qd and Qs are quantity demanded and supplied in millions of metric tonnes, respectively. If the market is at competitive equilibrium, then calculate producer surplus, consumer surplus, total expenditure, total variable cost and total social benefit for the world coal market. Draw appropriate diagrams.