Y = C + I + G + (X - M)
Given:
C = 1060 + 0.8Y_d
I = 2000
G = 800
X = 2000
M = 300 + 0.7Y
t = 0.3
c. Find equilibrium income:
Net taxes = tY
Disposable income = Y - tY = Y (1 - 0.3) = 0.7Y
So,
C = 1060 + 0.8 \cdot 0.7Y = 1060 + 0.56Y
Equilibrium condition:
Y = C + I + G + (X - M)
Y = 1060 + 0.56Y + 2000 + 800 + 2000 - (300 + 0.7Y)
Y = 1060 + 2000 + 800 + 2000 - 300 + 0.56Y - 0.7Y
Y = 5560 - 0.14Y
Y + 0.14Y = 5560
1.14Y = 5560
Y = \frac{5560}{1.14}
Y = 4877.19298
Rounded:
Y_e=4877
d. If the state decides to increase taxes by 40%:
t \text{ (new) } = 0.3 \cdot 1.4 = 0.42
New disposable income:
Y_d = Y - tY = Y(1 - 0.42) = 0.58Y
C = 1060 + 0.8 \cdot 0.58Y = 1060 + 0.464Y
New equilibrium condition:
Y = 1060 + 0.464Y + 2000 + 800 + 2000 - (300 + 0.7Y)
Y = 1060 + 2000 + 800 + 2000 - 300 + 0.464Y - 0.7Y
Y = 5560 - 0.236Y
Y + 0.236Y = 5560
1.236Y = 5560
Y = \frac{5560}{1.236}
Y \approx 4499.3
Rounded:
Y_e=4499