Chester Consultants purchased a building for $430,000 and depreciated it on a straight-line basis over 40 years. The estimated residual value was $70,000. After using the building for 20 years, Chester realized that the building would remain useful only 14 more years. Starting with the 21st year, Chester began depreciating the building over the newly revised total life of 34 years and decreased the estimated residual value to $12,980. Record depreciation expense on the building for years 20 and 21.