Answer:
$2,250
Explanation:
Given;
Cost of machine = $100,000
Residual value = $10,000
Useful life = 10 years
Annual depreciation = (Cost - Residual value ) Ă· useful life
= ($100,000 - $10,000 ) Ă· 10
= $90,000 Ă· 10
= $9,000 per year
Duration from  October 1, 2018 to December 31, 2018 in year = [tex]\frac{3}{12}[/tex] years
= 0.25 year
therefore,
Depreciation expense for the year ended December 31, 2018
= Â Annual depreciation Ă— Duration
= $9,000 Ă— 0.25
= $2,250