supply and demand
posted by shannon .
I'm looking for help on the third part of this question. I've included preceding questions/answers to show where I'm at. I don't know what to do next.
Suppose that a market is described by the following supply and demand equations:

Question 2 Suppose the demand and supply for milk is describe by the following equations: QD= 600 – 100P; QS=150+150P,where P is price in dollars, QD is quantity demanded in millions of gallons per year, and QS is quantity supplied in millions of gallons per year. Create demand and supply tables corresponding to these equations. (4 marks) Graph supply and demand and determine equilibrium price and quantity. (5 marks) Confirm your answer to (b) by solving the equations mathematically. (3 marks) Would government set price of $4 create surplus or shortage of the milk? How much? Is $4 a price ceiling or a price floor? (3 marks)