An industrial lift truck has been in service for several years, and management is contemplating replacing it. a planning horizon of five years is to be used in the replacement study. the old lift truck (defender) has a current mv of $7,000. if the defender is retained, it is anticipated to have annual operating and maintenance costs of $8,000. it will have a zero mv at the end of five additional years of service. the new lift truck (challenger) will cost $22,000 and will have operating and maintenance costs of $5,100. it will have a mv of $9,000 at the end of the planning horizon. using a pw comparison and marr before taxes of 20%, determine the preferred alternative.