Machine A costs $9000 to purchase and $5000 per year to operate. It lasts for 6 years, and has no salvage value at the end of its life. Machine B costs $16,000 to purchase and $4000 per year to operate. It lasts for 9 years and has a salvage value of $4000 at the end of its life. Compare the two machines on the basis of net present worth using an interest rate of 10%, compounded annually and the repeated projects approach?