Suppose an economy is described by the following macroeconomic variables:

Consumption function: C = 100 + 0.8(Y-T)
Investment function: I = 50
Government spending: G = 200
Tax function: T = 0.2Y
Net exports: NX = 50 - 0.1Y
Money demand function: Md = 0.5Y - 100r
Money supply: Ms = 300

where C is consumption, I is investment, G is government spending, T is taxes, Y is real GDP, NX is net exports, Md is money demand, r is the interest rate, and Ms is money supply.

a) Calculate the equilibrium level of real GDP and the interest rate.

b) Suppose the government increases spending by 100. What is the new equilibrium level of real GDP and interest rate?

c) Calculate the government spending multiplier, the tax multiplier, and the total multiplier.