Related to the
Economics in Practice on p. 50: The Amazon Kindle and the electronic textbooks available for the Kindle are complementary goods. Electronic textbooks and traditional, hard-copy textbooks are substitute products. If the price of the Kindle decreases
◦ demand for the Kindle increases and demand for traditional, hard-copy textbooks decreases.
◦ the quantity of Kindles demanded increases and demand for electronic textbooks increases.
◦ demand for the Kindle increases and the quantity of electronic textbooks demanded increases.
◦ the quantity of Kindles demanded increases and the quantity of electronic textbooks demanded increases.