Riverbed Company owns a $7,600-$acre tract of timber purchased in $2006$ at a cost of $$1,560$ per acre. At the time of purchase, the land was estimated to have a value of $$360$ per acre without the timber. Riverbed Company has not logged this tract since it was purchased. In $2020,$ Riverbed had the timber cruised. The cruise $($appraiser$)$ estimated that each acre contained $9,600$ board feet of timber. In $2020,$ Riverbed built $10$ miles of roads at a cost of $$8,090$ per mile. After the roads were completed, Riverbed logged and sold $4,200$ trees containing $1,020,000$ board feet.

$($a$)$

Determine the cost of timber sold related to depletion for $2020.($Round answer to $0$ decimal places, e$.$g$.5,125.)$

Cost of timber sold $

$($b$)$

If Riverbed depreciates the logging roads on the basis of timber cut, determine the depreciation expense for $2020.($Round answer to $0$ decimal places, e$.$g$.5,125.)$

Depreciation expense

$