The macro economy of a certain country is described by the following set of equations: Consumption: C=0.8(Y-T) + 30 Investment: 1=-2r+ 40 Government expenditure: G-30 Tax: T-0.25Y+20 The equilibrium condition of the monetary market is: 64/P=0.8Y-8r+32 When P=1/2, how much is the equilibrium national income? A. 180 B. 200 C. 360 D. 400 E. None of the above