When price goes up demand will go down (inverse relationship). Price goes up when demand increases, supply decreases or both.This diagram shows price rising because of an increase in demand. A quick and comprehensive intro to Supply and Demand. Supplyis how much of a good or serviceis available. Demand is how much of a good or service people are willing to buy. Overall we were in and out of the dealership in 40 min. The price of a good or service in a marketplace determines the quantity that consumers demand. Inverse Relationship of Price and Demand. The aggregate demand curve illustrates the relationship between two factors: the quantity of output that is demanded and the aggregate price level.