One variety of this economic concept arises from maximizing utility within 
One variety of this economic concept arises from maximizing utility within a fixed budget, and another arises from setting a target level of utility and minimizing cost. Those are elated to each other by the Slutsky equation and are known as its Marshallian and Hicksian forms. In macroeconomics, this is equal to the sum of consumer spending, government spending, private investment, and net exports, called its aggregate form. For 10 points, identify this economic concept which describes the willingness of consumers to pay a price for a good or service, often paired with supply.
One variety of this economic concept arises from maximizing utility within a fixed budget, and another arises from setting a target level of utility and minimizing cost.
{demand}