the following set of equations describe a hypothetical closed economy with government and central bank:

C=200+0.25Y _D

I=150+0.25Y- 1000i

G=250

T=200

M_D= 2Y-8000_i

M_s=1600

Where C is the consumption, Y_D is the real GDP, I is the investment, G is the government expenditure, T is the lump-sum tax, i is the interest rate, M_D is the (real) money demand, and M_S is the (real) money supply.

a. in the money market equilibrium, money demand, is equal to money supply. that is M_D=M_S. from this derive Y as a function of i.