janko wellspring inc. has a pump with a book value of $43,000 and a 4-year remaining life. a new, more efficient pump, is available at a cost of $64,000. janko can also receive $9,900 for trading in the old pump. the new pump will reduce variable costs by $13,900 per year over its four-year life. the costs not relevant to the decision of whether or not to replace the pump are: