A machine which cost $500,000 is acquired on October 1, 2020. Its estimated salvage value is $50,000 and its expected life is eight years.

(1) Calculate depreciation expense for 2020 and 2021 by each of the following methods, showing the figures used.

(a) Double-declining balance

(b) Sum-of-the-years'-digits

(2) At the end of 2021, which method results in the larger accumulated depreciation amount?

Please clearly explain and show your work