Revision of depreciation A building with a cost of dollar 1, 200,000 has an estimated residual value of dollar 250,000. has an estimated useful life of 40 years and is depreciated bv the straight-line method What is the amount of the annual depreciation? What is the book value at the end of the twenty-eighth year of ? If at the start of the twenty-ninth year it is estimated that the remaining life is 10 years and that the residual value is dollar 180,000 what is the depreciation expense for each