Sheffield Corp. acquires a coal mine at a cost of $1910000. Intangible development costs total $350000. After extraction has occurred, Sheffield must restore the property (estimated fair value of the obligation is $184000), after which it can be sold for $203000. Sheffield estimates that 6000 tons of coal can be extracted. What is the amount of depletion per ton?

a. 407

b. 339

c. 318

d. 374