Machinery purchased for $$60,000$ by Tom Brady Co$.$ in $2016$ was originally estimated to have a life of $8$ years with a salvage value of$$4,000$ 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 $$4,500$ at the end of that time. Assume straight$-$line depreciation.