A machine with a four$-$year estimated useful life and an estimated $15$ percent salvage value was acquired on January

$1,2019.$ On December $31,2021,$ the accumulated depreciation using the sum$-$of$-$year's digits method would be

a$.($Original cost less salvage value$)$ multiplied by $\frac{9}{10}$

b$.$ Original cost multiplied by $\frac{9}{10}$

c$.$ Original cost multiplied by $\frac{9}{10}$ less total salvage value

d$.($Original cost less salvage value$)$ multiplied by $\frac{1}{10}$