You can continue to use your less efficient machine at a cost of $8, 000 annually for the next five years. Alternatively, you can purchase a more 5-year efficient machine for $12, 000 plus $5, 000 annual maintenance. At a cost of capital of 15%, you should: Buy the new machine and save $388 in equivalent annual costs. Keep the old machine and save $388 in equivalent annual costs. Keep the old machine and save $580 in equivalent annual costs. Buy the new machine and save $600 in equivalent annual costs