Answer:
The journal entry is as follows:
Inventory A/c Dr. $73,500
To accumulated depletion A/c $73,500
(To record depletion)
Workings:
Depreciable cost:
= cost of coal mine + Intangible development cost + estimated fair value of obligation - sale value
= $400,000 + $100,000 + $80,000 - $160,000
= $420,000
Depreciation per ton = Depreciable cost ÷ Tons of coal extracted
= $420,000 ÷ 4,000
= $105
Inventory = Depreciation per ton × tons are extracted the first year
= $105 × 700
= $73,500