Listed below are some changes in (shifts in)

demand for various items. In each case, the change in demand has been caused by a change in the price of a substitute or of a complement. Explain whether the price of the substitute or complement must have increased or decreased.

a. A rise in the demand for a dashboard global positioning-

system device follows a change in the price of automobiles, which are complements.

b. A fall in the demand fore-book readers follows a change in the price of e-books, which are complements.

c. A rise in the demand for tablet devices follows a change in the price of ultra thin laptop computers, which are substitutes.

d. A fall in the demand for physical books follows a change in the price of e-books, which are substitutes.