Hi, I got wrong for the Sum-of-the-years'-digits, can you tell me how to solve this and what is the answer for this part? Thanks.

Problem 11-2 Your answer is partially correct. Try again. The cost of equipment purchased by Coronado, Inc, on June 1, 2017, is $89,890. It is estimated that the machine will have a $5,050 salvage value at the end of its service life. Its service life is estimated at 7 years, its total working hours are estimated at 42,420, and its total p the machine was operated 5,555 hours and produced 48,480 units. n is estimated at 530,250 units. During 2017, the machine was operated 6,060 hours and produced 55,550 units. During 2018 Compute depreciation expense on the machine for the year ending December 31, 2017, and the year ending December 31, 2018, using the following methods. (Round depreciation per unit to 2 decimal places, e.g. 15.25 and final answers to 0 decimal places, e.g. 45,892.) 2017 2018 (a) Straight-line (b) Units-of-output (c) Working hours (d) Sum-of-the-years'-digits (e) Double-declining-balance (twice the straight-line rate) 1212 7756.8 1212 21210 18180 14982 21402