Could you please show detail calculation for the following:

The economy of Greenoa is represented by the following system of equations:

Y = C + I + G + X - M

C = 75 + 0.9(Y-T)

I = 200 - 100r

G = 150

X = 50

M = 0.1Y

T = 100

where Y is GDP, C is consumption, I is investment, G is government expenditures, X is exports of goods and services, M is imports of goods and services, T is taxes, and r is the interest rate. What is the government expenditure multiplier?

Select one:

a. 150

b. 10

c. infinity ()

d. 50

e. 5