Consider the demand and supply equations for world coal market:

Qd= 7875000-2850P

Qs= 2400P

Where P is price per tonne. Qdand Qsare 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.