Suppose the demand and supply for eggs in the United States are given by Qd = 100 - 20P and Q s = 10 + 40P respectively, where Qd = millions of dozens of eggs Americans would like to buy each year; Qs = millions of dozens of eggs US farms would like to sell each year; and P = price per dozen eggs. Do the following, clearly writing the units of measurement wherever required:

1. Write the demand schedule and then draw the demand curve 

2. Write the supply schedule and then draw the supply curve

3. Find the equilibrium price and quantity mathematically by solving the equations 

4. Graph the demand and supply curves (as before) and identify the equilibrium price and quantity

5. Why is an equilibrium "stable" from an economy's point of view?