Answer:
$3
Explanation:
A price floor is when the government or an agency of the government sets the minimum price of a product. A price floor is binding if it is set above equilibrium price.
Price ceiling is when the government or an agency of the government sets the maximum price for a product. It is binding when it is set below equilibrium price.
Equilibrium price is the price at which quantity demand equal quantity supplied. Above equilibrium price there is a surplus - quantity supplied exceeds quantity demanded.
Below equilibrium price there is a shortage - quantity demanded exceeds quantity supplied
Shortage = $12 - $9 = $3
