Frankel Feed purchased a new machine on January 1, 2010, relevant information follows: It is now the beginning of year 6 and the management reevaluated the estimates related to the machine. Compute the depreciation expense for year 6 under each of the following independent cases: Event Case A The estimated total useful life is changed to 15 years, residual value is unchanged. B The residual value is changed to $1,000; useful life unchanged. C The estimated total useful life is changed to 7 years and the residual value is changed to $3,000