An electric switch manufacturing company is trying to decide between three different assembly methods. Method A has an estimated first cost of $30,000, an annual operating cost (AOC) of $4,000, and a service life of 2 years. Method B will cost $70,000 to buy and will have an AOC of $3,000 over its 4-year service life. Method C costs $115,000 initially with an AOC of $3,000 over its 8-year life. Methods A and B will have no salvage value, but Method C will have equipment worth 6% of its first cost