GreenLawns provides a lawn fertilizer and weed control service. In addition, the company is adding a special aeration treatment as a low-cost extra service option, which it hopes will help attract new customers. Management plans to promote this new service in two media: radio and direct-mail advertising. A media budget of $10,000 is available for this promotional campaign. Based on past experience in promoting its other services, GreenLawns obtained the following estimate of the relationship between sales and the amount spent on promotion in these two media.