I have a question. Why do they credit equipment of $98,000 not $150,000?

I thought when they dispose asset, they take remove the historical cost of the asset.

Palo Alto Company owns equipment that produces mobile phone cases. The equipment was purchased at a cost of $150,000 two years ago and is estimted to have a 6-year useful life with straight-line depreciation expense of $25,000 per year. In the current period, management discovers that the machine has begun to operate much less efficiently and produce fewer units. This has the effect of reducing its operating cash flow to $15,000 per year for the next four years and its future estimated market value sales price to $20,000. The current fair value of the equipment is $52,000. - Current book value: $150,000$50,000=$100,000 - Undiscounted future cash flows: ($15,0004)+$20,000=$80,000 - Book value vs. cash flows: $100,000 exceeds $80,000= Asset is impaired. - Amount of impairement loss: $100,000$52,000=$48,000 Journal entry: Record the impairment loss as follows: first eliminate accumulated depreciation (a debit). Then adjust the asset cost down to current fair value by crediting the asset for the difference between the original cost and the current market value (fair value). Result: the asset has a "new" cost of $52,000 which becomes the basis for depreciation over the asset's remaining life. The impairment loss is permanent and a higher value cannot be restored if the asset value increases later. Notice that although a loss is recorded in the current period, future depreciation expense will be reduced because of the new lower recorded cost (minus new residual value), increasing future net income. An impairment loss should be reported as part of continuing operations, before tax. The clearest reporting is in the "other" section of the income statement. Footnote disclosure of the details and estimating methods is also required