The manager of a small gas station observes that while gasoline sales have been steady, the service side of the business has declined, and mechanics are often idle. he decides to offer a promotion—a $20 off coupon for an oil change that is to be mailed to 800 households within a two-mile radius from the gas station. the cost of printing and mailing is $1,000. the normal cost of an oil change is $40. materials and labor per oil change cost is $15. how many additional maintenance service jobs must result for the promotion to break even?