Swifty Corporation acquires a coal mine at a cost of $ 1700000. Intangible development costs total $ 366000. After extraction has occurred, Swifty must restore the property (estimated fair value of the obligation is $ 171000), after which it can be sold for $ 211000. Swifty estimates that 5000 tons of coal can be extracted. What is the amount of depletion per ton? $ 370 $ 405 $ 447 $ 340