Problem
Assume the following demand and supply functions
Qd= -10p + 80            Qs= 20p - 10
a)	Draw these functions
b)	Determine the equilibrium price and quantity and label the equilibrium, the price at equilibrium, and the quantity exchanged
c)	Suppose that supply shifts to Qs= p -2 with no change in demand. Determine the new equilibrium price and quantity.
d)	Calculate the surplus of the consumer and producer at the new equilibrium.