P=-2Q_d+40

P=3Q_s+10

a. Find the equilibrium price and quantity.

b. The government imposes a tax of

*t*per unit sold. Show that the equilibrium quantity is given by

Q= 6 - 0.2t

and find a similar expression for the equilibrium price.

c. If the equilibrium quantity is known to be 4, calculate the value of

*t*.

How much tax revenue is raised by the government?