An industry has a demand of Qd = 150 -15P and a supply curve of Qs = 10P -25. (a) What is the equilibrium price and quantity?

An industry has a demand of Qd = 150 -15P and a supply curve of Qs = 10P -25.(a) What is the equilibrium price and quantity? [Hint: Recall what is the condition for equilibrium.](b) Suppose demand increases to Qd = 200-15P. What is the equilibrium price and quantity? [Hint: This is the new demand equation and the supply has still not changed.]