Macroeconomics 13th Edition by William Baumol ,Alan Blinder

Exercise 8

Find the equilibrium level of GDP demanded in an economy in which investment is always $300, net exports are always -$50, the government budget is balanced with purchases and taxes both equal to $400, and the consumption function is described by the following algebraic equation:
C = 150 + 0.75 DI
( Hint: Do not forget that DI = Y - T. )