Consumption Function is C = 500+ 0.9 Y where Y in the income in the economy. At equilibrium level of income, AS=AD Y= C+I => Y= 500 + 0.9 Y + 3,000 => Y - 0.9 Y = 500 + 3,000 => 0.1 Y = 3,500 => Y = 3,500/ 0.1 = 35,000.