E-F:10-21 Changing an assets useful life and residual value Salem Hardware Consultants purchased a building for $540,000 and depreciated it on a straight-line basis over a 40-year period. The estimated residual value is $100,000. After using the building for 15 years, Salem realized that wear and tear on the building would wear it out before 40 years and that the estimated residual value should be $88,000. Starting with the 16th year, Salem began depreciating the building over a revised