Machinery purchased for $60,000 by2003 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 2008, 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.