Suppose an economy is represented by the following equations.

Consumption functionC = 200 + 0.8Yd

Planned investmentI = 400

Government spendingG = 600

ExportsEX = 200

ImportsIM = 0.1Yd

Autonomous TaxesT = 500

Marginal Tax Ratet=0.2

Planned aggregate expenditureAE = C + I + G + (EX - IM)

By using the above information calculate the equilibrium level of income for this economy and explain why fiscal policy becomes less effective in an open economy