help with the following:

C=250 mil +0,9 Yd

I=175 mil

G= 310 mil

X = 170 mil

Z = 120 mil

T = 0,25Y

Yf=R3 100 million

Equilibrium income : Y= C+I+G+(X-Z)

Disposable income: Yd=(1-t)Y

a.Calculate the multiplier

b.Calculate the equilibrium level of income based on the calculated value of the multiplier in a.

c.By approximately how much should investment spending be raised to achieve full employment?

d.How much will the multiplier and the equilibrium level of income change by including induced imports (m= 0.11?)