A company is evaluating two machines. Both machines meet the company's quality standard. Machine A costs $40 000 initially and $1000 per year to maintain. Machine B costs $24 000 initially and $2000 per year to maintain. Machine A has a six-year useful life and Machine B has a three-year useful life. Both machines have zero salvage value. Assume the company will continue to replace worn-out machines with similar machines and that the discount rate is 7%. Which machine should the company purchase.