What is the expected after-tax cash flow from selling a piece of equipment if Litchfield Design purchases the equipment today for 50,000 dollars, the tax rate is 40 percent, the equipment is sold in 3 years for 8,000 dollars, and MACRS depreciation is used where the depreciation rates in years 1, 2, 3, 4, and 5 are 30 percent, 27 percent, 25 percent, 11 percent, and 7 percent, respectively?