(A) In business, the difference between the sale price and the production cost of a product is the unit profit. In economics, the sum of the unit profit, the unit depreciation cost, and the unit labor cost is the unit value added.
(B) The Income Method: adding factor incomes. Here GDP is the sum of the incomes earned through the production of goods and services.
(C) An expenditure is a payment in cash or barter credits, or the incurrence of a liability by an entity, in exchange for goods or services. Evidence of the documentation triggered by an expenditure is a sales receipt or an invoice. Organizations tend to maintain tight controls over expenditures, to keep from incurring losses.