Duluth Ranch, Inc. purchased a machine on January 1, 2018. The cost of the machine was $20,000. Its estimated residual value was $6,000 at the end of an estimated 5-year life. The company expects to produce a total of 20,000 units. The company produced 800 units in 2018 and 1,250 units in 2019. Required:

1. Calculate depreciation expense for 2018 and 2019 using the straight-line method.
2. Calculate the depreciation expense for 2018 and 2019 using the units-of-production method.
3. Calculate depreciation expense for 2018 through 2022 using the double-declining balance method.