Two advertising media are being considered for promotion of a product. Radio ads cost $400 each, while newspaper ads cost $600 each. The total budget is $7,200 per week. The total number of ads should be at least 15, with at least 2 of each type, and there should be no more than 19 ads in total. The company does not want the number of newspaper ads to exceed the number of radio ads by more than 25 percent. Each newspaper ad reaches 6,000 people, 50 percent of whom will respond; while each radio ad reaches 2,000 people, 20 percent of whom will respond. The company wishes to reach as many respondents as possible while meeting all the constraints stated. If this is formulated as a LP model, with R = number of radio ads placed and N = number of newspaper ads placed, the correct set of constraints would be:

R+N >= 15; R+N <= 19; 400R+600N <= 7200; 1.25R - N <= 7200; R >; N >

R+N >= 15; R+N >= 19; 400R+600N <= 7200; 1.25R - N <= 7200; R >; N >; R, N >= 0

R+N >= 15; R+N <= 19; 400R+600N <= 7200; 1.25R - N <= 7200; R >; N >; R, N >= 0

R+N >= 15; R+N <= 19; 400R+600N <= 7200; 1.25R + N <= 7200; R >; N >; R, N >= 0

R+N <= 15; R+N <= 19; 400R+600N <= 7200; 1.25R - N <= 7200; R >; N >; R, N >= 0