Robert Smith Company purchased a new machine for its assembly process on June 1, 2015. The cost of this machine was $122,000. The company estimated that the machine would have a salvage value of $12,000 at the end of its service life. Its life is estimated at 5 years.

Required: Compute the depreciation expense under the following methods:

1. Straight-line method

2. Sum-of-the-years-digits

3. Double declining balance