Machinery purchased for $$60600$ by crane co in $2021$ was originally estimated to have a life of $8$ years with a salvage value of $$4040$ at the end of that time. depreciation has been entered for $5$ years on this basis. in $2021,$ it is determined that the total estimated life should be $10$ years with a salvage value of $$4545$ at the end of that time. assume straight line depreciation.