you have purchased an equipment costing $20,000. the equipment will be used for two years, and at the end of two years, its salvavage value is expected to be 10,000. the equipment will be used for 6,00o hours during the first year and 8,000 hours the second year. the ecpected annual net savings will be 30,000 durning the first year and 40,000 during the second year. if your interst rate is 10%, what would be the equivalent net savings per machine hour?