On august 1, 2015, hang seng ltd purchased a machine for $84000 cash. The machine is expected to last 5 years and have a residual value of $12000. hang seng calculate depreciation to the nearest month. using straight line depreciation, calculate the book value of this machine at December 31, 2016. using double declining balance depreciation, calculate the accumulated depreciation for this machine at December 31,2016