tolong dengan caranya ya, makasih

angka pengganda subsidi = k = mpc/mps
mpc = 1 - mps
k = (1 - mps) / mps
4 = (1 - mps) / mps
4mps = 1 - mps
4mps + mps = 1
5mps = 1
mps = 1/5 = 0,2
break even = a/mps
300 = a/0,2
300(0,2) = a
a = 60
S = -a + mps.Y
S = -60 + 0,2Y
keseimbangan pendapatan terjadi saat S = I
-60 + 0,2Y = 25
0,2Y = 25 + 60
0,2Y = 85
Y = 85/0,2
Y = 425