Gull Corp. is considering selling its old popcorn machine and replacing it with a newer one. The old machine has a book value of $5,000, and its remaining useful life is five years. Annual costs are $4,000. A high schoel is willing to buy it for $2,000. New equipment would cost $18,000 with annual operating costs of $1,500. The new machine has an estimated useful life of five years. Prepare a differential analysis.