As with substitutes, you can memorize how changes in the price of complements affects demand, but ultimately it is easier to remember the underlying logic. Still, the table below summarizes what we've learned about the effect of the price of complements on demand.

Price of Complement	Demand Shift

The reasoning here is simple, if one remembers that complementary goods are consumed together. If the price of one of the goods rises, this increase in price will shift back (decrease) the demand for the other good, as the combined price of the jointly consumed good has risen; if the price of one of the goods falls, this decrease in price will shift out (increase) demand for the other good as the price of the jointly consumed good falls.