An enterprise is planning a new radio, TV, and newspaper advertising campaign. A radio commercial costs $300, a TV commercial costs $800, and a newspaper ad costs $150. A total maximum budget of $30,000 is allocated to the campaign; however the number of ads in each campaign cannot exceed 75% of the total number of ads. It's estimated that a radio commercial will reach 1,750 people, a TV commercial will reach 5120, and a newspaper ad is expected to reach 870 people. We wish to use integer programming to determine how we should allocate the available budget into the three advertisement types.

What is the optimal number of newspaper ads?