Holman company owns equipment with an original cost of $95,000 and an estimated salvage value of $5,000 that is being depreciated at $15,000 per year using the straight-line depreciation method, and only prepares adjustments at year-end. the adjusting entry needed to record annual depreciation is:

Depreciation is a way not only to recognize the lost value over time of an asset, but also a way to recognize the expense of the asset over time. To this end, we want to see the value of the asset get smaller, and a piece of the asset on the the income statement ever period. 
The depreciation base is 95,000 -5,000 = 90,000, and the depreciation period is 90,000/15,000 = 6 years.
The journal entry every year will be 
Dec. 31
Debit: Depreciation expense 15,0000
Credit: Accumulated Depreciation       (15,000)
Accumulated depreciation is a *contra-asset* account on the balance sheet that reduces the value of the the depreciable asset.