20. Barton Corporation acquires a coal mine at a cost of $1,800,000. Intangible development costs total $360,000. After extraction has occurred, Barton must restore the property (estimated fair value of the obligation is $180,000), after which it can be sold for $210,000. Barton estimates that 6,000 tons of coal can be extracted. What is the amount of depletion per ton? a. $390 b. $355 c. $320 d. $300