The demand function for DVD players has been estimated to be QPlayer = 134 - 1.07PDVD + 46Pm - 2.1PDVD - 5M, where QPlayer is the quantity of DVD players, PDVD is the price of a videocassette, Pm is the price of a movie, PPlayer is the price of a DVD player, and M is income. Based on this information, answer the following questions. a. Are DVD players normal or inferior goods? b. Are movies substitutes or complements for DVD players? c. What additional information is needed to calculate the price elasticity of demand for DVD players?