58. Complementary and Substitute Commodities In a survey, it was determined that the demand equation for DVD players is given by x = f(p, q) = 10,000 - 10p - e0-5q and the demand equation for blank DVD discs is given by y = g(p, q) = 50,000 - 4000q - 10p where p and q denote the unit prices, respectively, and a and y denote the number of DVD players and the number of blank DVD discs demanded each week. Determine whether these two products are substitute, complementary, or neither