CSC Corp just purchased equipment valued at $200,000 and it is expected to have a useful life of 6 years and a residual value of $20,000. Calculate the annual depreciation using the straight-line method and what is the depreciation rate for each of the 6 years of useful life?

a. $30,000 & 16.7%

b. $30,000 & 15.0%

c. $33,333 & 15.0%

d. $36,666 & 15.0%