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A company purchases machinery costing $60,000 in October of 2017. Five years later, management discovers better, more efficient machine that could be purchased for $80,000 to replace the existing machine. Management has determined that they are able to sell the original machine for $15,000. In making the decision about buying the new machine, how much are total sunk costs? $60,000 $80,000 $15,000 $20,000