"company x has been contracting its overhauling work to company y for $30,000 per machine per year. company x estimates that by building a $598,000 maintenance facility with a life of 16 years and a salvage value of $50,000 at the end of its life, it could handle its own overhauling at a cost of only $16,000 per machine per year. what is the minimum annual number of machines (as an integer) that company x must operate to make it economically feasible to build its own facility? (assume an interest rate of 12%.) hint: calculate the annual equivalent cost of the maintenance facility."