Equipment with a cost of $579,600 has an estimated residual value of $62,100, has an estimated useful life of 15 years, and is depreciated by the straight-line method. a. Determine the amount of the annual depreciation. $ b. Determine the book value at the end of the 8 full years of use. $ c. Assuming that at the start of the year 9 the remaining life is estimated to be 12 years and the residual value is estimated to be $55,200, determine the depreiation expense for each of the remaining 12 years. $