Answer:
accumulated depreciation = 241667
depreciation for 2016 = 6800
book value as December 2017 = 240000
Step-by-step explanation:
solution 
we know SLM depreciation per month is express as
depreciation = 

put here value 
depreciation = 

depreciation = 100000
and 
accumulated depreciation as of 31st December is 
accumulated depreciation = 

accumulated depreciation = 241667
and
depreciation per hour is 
depreciation = 

depreciation = 

depreciation per hour = 8
so depreciation for 2016 = 8500 × 8 = 6800
and
as depreciation by sum of year of digit method 
depreciation = 

so here sum of years digit = 1 + 2 + 3 + 4 = 10
so 1st year depreciation = 
 = 160000
 = 160000
and next year depreciation = 
 = 120000
 = 120000
so depreciation from august 2016 to july 2017 = 160000
and depreciation from august 2017 to December 2017 = 
 = 50000
 = 50000
so book value as December 2017 = 450000 - 160000 - 50000
 book value as December 2017 = 240000