Martin is a marketing manager for a start-up company. Martin approached a specialized marketing firm to help him develop a weekly marketing campaign for his company. There are two advertisement media available (Radio and TV). Radio ads cost $400 per ad, while TV ads cost $600 per ad. The total budget available for Marting is $7,200 per week. The total number of ads should be at least 15, with at least 2 ads of each type. Each TV ad reaches 6,000 people, while the number of people who are reached by each radio ad is 2,000. The company wishes to reach as many people as possible. Formulate this problem as a linear programming model (list the decision variables, objective function, and the constraints)