Compare to units, A and B. A has a new cost of $42,000, at life expectancy of 14 years, a salvage value of $4,000, and an annual operating cost of $3,000. B has a new cost of $21,000, a life expectancy of 7 years, a salvage value of $2,000, and an operating cost of $5,000. Assume an annual interest rate of 7%. Which of the two units would you recommend? Why?