A high-speed electronic assembly machine was purchased two years ago for $50,000. At the present time, it can be sold for $25,000 and replaced by a newer model having a purchase price of $43,000; or it can be kept in service for a maximum of one more year. The new assembly machine, if purchased, has a useful life of not more than two years. If the before-tax MARR is 12%, when should the old assembly machine be replaced? Use the following data table for your analysis. Challenger Defender Year Market Value O&M Costs Market Value 0&M Costs $43,000 30,000 25,000 $11,500 13,500 $25,000 16,500 $13,500