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The assetsection of the January 1, 20X7, balance sheet of Petticoat Company includes amachine which was acquired on January 1, 20X3. The machine's original cost was $500,000, and the estimated life wasdetermined to be 10 years. The estimatedresidual value was zero, and the straight-line method of depreciation waschosen. If operating income before depreciation is$90,000, the rate of return on average net book value for 20X7 is: