On 10/1/19, SAP Co. purchased equipment for $200,000. The equipment has a residual value of $20,000, an estimated useful life of 10 years, during which time it is expected to produce 80,000 units. The equipment produced 20,000 units in 2019 and 40,000 units in 2020. On 1/1/21 the equipment was sold for $125,000. Given this information, please: (1) calculate the depreciation expense and accumulated depreciation for year 2019 and 2020; (2) calculate the gain or loss on the sale, assuming that SAP Co. uses: a) Straight-Line method b) Units-of-Activity (units of production) method c) Double-Declining-Balance method