on january 1, year 1, warren co. purchased a $600,000 machine, with a five-year useful life and no salvage value. the machine was depreciated by an accelerated method for book and tax purposes. the machine's carrying amount was $240,000 on december 31, year 2. on january 1, year 3, warren changed retroactively to the straight-line method for financial statement purposes. warren can justify the change. warren's income tax rate is 30%. in its year 3 income statement, what amount should warren report as a prior period adjustment as result of this change?