at the beginning of the year, flint inc. is considering whether to repair and retain an existing machine, or to replace it with a new machine. the following information is available to analyze this decision: machine overhaul costs (last year) $6400 repair costs (current year) 2500 annual operating costs (existing machine) 13300 annual operating costs (new machine) 8600 which of the costs being considered for this decision represents a sunk cost?