In this lesson I'm going to illustrate and explain how to derive a demand equation using data from a demand schedule or a demand curve. A written rent demand must give you at least 14 days' notice to pay the rent before a court case can be started.Price goes up when demand increases, supply decreases or both. This diagram shows price rising because of an increase in demand. There is an inverse relationship between the supply and prices of goods and services when demand is unchanged. In economics, demand is the quantity of a good that consumers are willing and able to purchase at various prices during a given time. Consider the market for Oranges. For each of the following changes in the market, draw the effect of that change on the graph. If your landlord takes any money out of the security deposit for damages, they must provide an itemized "receipt" describing the damage and its cost. If the price goes up, the quantity demanded goes down (but demand itself stays the same).