7. (10 points) The demand for housing D is given by the function: D = 100p'ar'i', where p is the price and r is the mortgage interest rate. Treat the mortgage rate exogenous as it is typically determined by the macroeconomic condition. The supply of housing is given by: S = A; where A is the quantity of existing housing stock. Parameters a, b are positive constants. a. What are the economic interpretations of the parameters a and b ? b. Solve for the equilibrium housing price, and carry out comparative static analysis with reSpect to all parameters