_ 'P' is the investment made on an equipment, 'S' is its salvage value and 'n is the life of the equipment in years. The depreciation for rath year by the sum-of years digit method will be$?

• A. (P - S)/n
• B. 1 - (P/S)1/m
• C. M/n x (P - S)
• D. 2(n - m + 1)/n(n + 1) x (P - S)