Macroeconomics 13th Edition by William Baumol ,Alan Blinder

Exercise 7

(More difficult) The demand and supply curves for T-shirts in Tourist town, U.S.A., are given by the following equations:
Q = 24,000 500 P Q = 6,000 + 1,000 P
where P is measured in dollars and Q is the number of
T-shirts sold per year.
a. Find the equilibrium price and quantity algebraically.
b. If tourists decide they do not really like T-shirts that much, which of the following might be the new demand curve
Q = 21,000 500 P Q = 27,000 + 500 P
Find the equilibrium price and quantity after the shift of the demand curve.
c. If, instead, two new stores that sell T-shirts open up in town, which of the following might be the new supply curve
Q = 4,000 + 1,000 P Q = 9,000 + 1,000 P
Find the equilibrium price and quantity after the shift of the supply curve.