Given the following information for a closed economy: Consumption function C = 60 + 0.8Yd, Investment I = 200, Government spending G = 400, Income tax T = 0.5Y. Calculate the equilibrium level of nati

Given $T = 0.5Y$:

The equilibrium level of national income is $\boxed{\text{1100 million francs CFA}}$.

Exports ($X$) = 300
Imports ($M$) = $0.2Y$
From part b, $C = 60 + 0.4Y$, $I = 200$, $G = 400$.

The new equilibrium level of national income is $\boxed{\text{1200 million francs CFA}}$.

d) The value of the multiplier in (c) can be found from the equilibrium equation $Y = \text{Autonomous Expenditure} + \text{Induced Expenditure}$. In part (c), we had $Y = 960 + 0.2Y$, which simplifies to $0.8Y = 960$. The multiplier is $\frac{1}{1 - \text{marginal propensity to spend}}$.

Marginal Propensity to Consume (MPC) = 0.8 (from $C = 60 + 0.8Y^d$)
Marginal Tax Rate ($t$) = 0.5 (from $T = 0.5Y$)
Marginal Propensity to Import (MPM) = 0.2 (from $M = 0.2Y$)

The value of the multiplier is $\boxed{1.25}$.

Since $X > M$, the country has a balance of payments surplus of 60 million francs CFA.

Since $T > G$, the country has a budget surplus of 200 million francs CFA.