Perfectly competitive Equilibrium. Fuel costs have risen quickly during recent years as consumption, refining and production costs have risen sharply

Perfectly competitive Equilibrium. Fuel costs have risen quickly during recent years as consumption, refining and production costs have risen sharply. Supply and demand conditions in the perfectly competitive domestic crude oil market are: Qs = -60 + 2P (Supply) and Qd = 90- P (Demand), where Q is the quantity in millions of barrels per day, and P is price per barrel.
Graph industry supply and demand curves. Determine both graphically and algebraically the equilibrium industry price/output combination.