Cabot Enterprise is analyzing two machines to determine which one it should purchase. Whichever machine is purchased will be replaced at the end of its useful life. The company requires a 15 percent rate of return and uses straight-line depreciation to a zero book value over the life of the machine. Machine A has a cost of $720,000, annual operating costs of $50,000, and a 8-year life. Machine B costs $350,000, has annual operating costs of $110,000, and a 5-year life. The firm currently pays no taxes. Which machine should be purchased and why?