19. The Spurling Group is considering using magazine outlets to advertise their online Web site. The company has identified seven publishers. Each publisher breaks down its subscriber base into a number of groups based on demographics and location. These data are shown in the table.

Publisher Groups Subscribers/Group Cost/Group A 5 460,000 $1,560 B 10 50,000 $290 C 4 225,000 $1,200 D 20 24,000 $130 E 5 1,120,000 $2,500 F 1 1,700,000 $7,000 G 2 406,000 $1,700 The company has set a budget of $25,000 for advertising and wants to maximize the number of subscribers exposed to their ads. However, publishers B and D are competitors and only one of these may be chosen. A similar situation exists with publishers C and G. Formulate and solve an integer optimization model to determine which publishers to select and how many groups to purchase for each publisher.