could you please explain

The Railway Corporation has an overhead crane that has an estimated remaining life of 9 years. The crane can be sold now for $9000. If the crane is kept in service, it must be overhauled immediately at a cost of $5000. Operating and maintenance costs will be $4000 per year after the crane is overhauled. The overhauled crane will have zero MV at the end of the 9-year study period. A new crane will cost $22000, will last for 9 years, and will have a $8000MV at that time. Operating and maintenance costs are $2000 per year for the new crane. The company uses a before-tax interest rate of 13% per year in evaluating investment alternatives