A company owns a milling machine that it is considering replacing. Its current market value is $30,000, but it can be productively used for four more years at which time its market value will be zero. Operating and maintenance expenses are $60,000 per year. The company can purchase a new milling machine, with the same functionality as the current machine, for $90,000. In four years the market value of the new machine is estimated to be $45,000. Annual operating and maintenance costs will be $35,000 per year. Should the old milling machine be replaced using a before-tax MARR of 10% and a study period of four years? Rubric: correct computation of values of defender and challenger , correct steps , and justification Hint: use present worth approach based on compound amount factor, not excel functions. Provide a justification for your decision. Computing the numeric answer(s) is not enough to get full credit.