Assume G-1 Designing Consultants purchased a building for $400,000 and depreciated it on a straight-line basis over 40 years. The estimated residual value was $55,000. After using the building for 20 years, G-1 realized that the building will remain useful only 15 more years. Starting with the 21st year, G-1 began depreciating the building over a revised total life of 35 years and decreased the residual value to $10,000. Record depreciation expense on the building for years 20 and 21.