If $C$ is the original value of the asset, $S$ is the scrap value, $n$ is the useful life of the asset and $D$ is the annual depreciation, then

$D=\frac{C-S}{n}$

The correct answer is Option (4) → $D=\frac{C-S}{n}$

Using the linear (straight-line) depreciation method:

Annual depreciation: $D = \frac{C - S}{n}$

Where:

• $C$ = original cost of the asset
• $S$ = scrap value of the asset at the end of useful life
• $n$ = useful life in years
• $D$ = annual depreciation