Positive XED (Substitutes): When the price of one product increases, the demand for the substitute product increases. Example: Tea and Coffee. Negative XED (Complements): When the price of one product increases, the demand for the complementary product decreases. Example: Printers and Ink Cartridges. Zero XED (Unrelated Goods): The change in the price of one product does not affect the demand for the other. Example: Bread and Cars.