The greatest portion of the expense is taken on the first year, with SUCCESSIVELY smaller amounts being taken on later years.
a. SUM OF THE YEARS DIGITS
b. DOUBLE DECLINING BALANCE
The TRADE IN VALUE or ESTIMATED SELLING PRICE at the end of its useful life.
The SALVAGE VALUE is deducted from the COST, and the remaining amount is divided by the ESTIMATED USEFUL LIFE of the asset.
NUMERATOR: the remaining years of the expected lifetime
DENOMINATOR: the sum of all the years of the asset’s life.
5+4+3+2+1 = 15.
In the first year, you would have depreciation expense of 5/15ths of the cost (less the SALVAGE VALUE).