Editing Complementary good (section)

==Examples==
[[File:Supply-and-demand.svg|thumb|alt=Supply and Demand curves.|Supply and demand of cars when the price of petrol decreases]]

An example of this would be the demand for [[car]]s and [[petrol]]. The [[supply and demand]] for cars is represented by the figure, with the initial demand <math>D_1</math>. Suppose that the initial price of cars is represented by <math>P_1</math> with a quantity demanded of <math>Q_1</math>. If the price of petrol were to decrease by some amount, this would result in a higher quantity of cars demanded. This higher quantity demanded would cause the demand curve to [[Demand curve#Shift of a demand curve|shift rightward]] to a new position <math>D_2</math>. Assuming a constant supply curve <math>S</math> of cars, the new increased quantity demanded will be at <math>Q_2</math> with a new increased price <math>P_2</math>. Other examples include automobiles and fuel, mobile phones and cellular service, printer and cartridge, among others.