Look at this question: "Suppose Y = $200, C = $140, G = $25, x-m = -5, and T = $25. What is Sp? What is I?" Here is the answer:
Yd = Y - T | C + Sp = Y - T | Sp = Y - T - C
Sp = Y - C - T = 200 - 25 - 140 = $35
I = Sp + (T - G) + (x-m) = $35
I = $35 + 0 - 5 = $30
I got this question wrong because I never would have said
I = Sp + (T - G) + (x-m)
I would have said
I = Sp + Sb + (T - G) + (x-m)
where Sb represents undistributed profits by the business sector
Why is Sb omitted?