4. Suppose that the money market of Econometallica has the following money supply and demand equations : Money Supply : M = 8000 Money Demand : M= 10,000 - 40,000r Where money is in billions of dollars and interest rates, r , is written as a decimal (e.g., an interest rate of 10 % would be written as .1 in the equation ). (a) Sketch the money supply and demand curves, putting the quantity of money on the horizontal axis and the interest rate (in percent) on the vertical axis. Indicate the slope and intercept of each curve