Answer:
$31,238.10
Explanation:
Straight line depreciation expense = (Cost of asset - Salvage value) / useful life
($510,000 - $18,000) / 7 = $70,285.71
Depreciation expense from 2017 to December 2019 would be = $70,285.71 x 3 = $210,857.14
Book value at the beginning of 2020 = $510,000 - $210,857.14 = $299,142.86
Depreciation expense from 2020 = ($299,142.86 - $18,000) / 9 = $31,238.10