Able Towing Company purchased a tow truck for 225,000 dollars on January 1,2019. It was originally depreciated on a straight-line basis over 10 years with an assumed residual value of 45,000 dollars. On December 31, 2021, before adjusting entries had been made, the company decided to change the remaining estimated life to 4 years (including 2021) and the residual value to $7,500. What was the depreciation expense for 2021?