Revision of depreciation A building with a cost of exist1, 200,000 has an estimated residual value of exist250,000, has an estimated useful life of 40 years, and is depreciated by the straight-line method. (a) What is the amount of the annual depreciation? (b) What is the book value at the end of the twenty-eighth year of use? (c) 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 exist180,000, what is the depreciation expense for each of the remaining 10 years