Question 5. (12 points) Consider a small open economy described by the following equations: Y = C + I + G + NX, Y = 5,000, G = 1,000, T = 1,000, C= 250 + 0.75(Y - T) I = 1,000 - 50r NX = 500 - 500 , r = r* = 5, where Y is income, I is investment, G is government spending, T is tax, r* is the world interest rate. a. (7 points) In this economy, solve for national saving, investment, the trade balance, and equilibrium exchange rate. b. (5 points) Now suppose that the world interest rate (r*) rises. Explain briefly what are the impacts on national saving, investment, the trade balance, and the equilibrium exchange rate.