Assume you have the following model of the expenditure sector:
Sp = C + I + G + NX
C = 400 + (0.8)YD
Io = 200
G = 300 + (0.1)(Y* - Y)
YD = Y - TA + TR
NXo = - 40
TA = (0.25)Y TRo = 50
What is the size of the output gap if potential output is at Y* = 3,000?