Can anyone help me to solve the following question?? I don't understand how to do part (c) and (d). its really urgent...please help! Many thanks: ) 18. Consider a simple goods market model: Consumption: C = a + bY Investment: I = ÃÂ± Ã¢Ëâ ÃÂ²i Government expenditure: G = G0 (a) Use a diagram of simple Keynesian model (Keynesian cross) to illustrate the equilibrium national output. You should clearly indicate the numerical values for the intercept and the equilibrium output in the diagram. (b) Assuming interest rate remains constant, calculate the government multiplier. (c) Call the equilibrium output as Y1 after the government expenditure increases by $1 under the assumption in (b). If interest rate is flexible, after the $1 increase in government expenditure, output in the goods-money market equilibrium is Y2. Use a diagram (donÃ¢â¬â¢t calculate the values) to indicate Y1 and Y2. (d) For (b) and (c), we assume general price level is fixed. If price is flexible, the equilibrium output is Y3. Illustrate Y1, Y2, and Y3 in the aggregate supply-aggregate demand model and in the IS/LM model.