The Quantity of Coffee Demanded, Q^D, Depends on the Price

The quantity of coffee demanded, Q^D, depends on the price of coffee, P , and the price of tea, P . The quantity of
c T
coffee supplied, Q^S, depends on the price of coffee, P , and the price of electricity, P , according to the following
c E
equation:
Q^D = 17 - 2 P + 10 P
c T
Q^S = 2 + 3 P - 5 P
c E
a. If the price of tea is $1.00 and the price of electricity is $0.50, what is the equilibrium price and quantity of coffee?
b. What is/are the endogenous variable(s) in this model?
c. What is/are the exogenous variable(s) in this model?