Online Inc. purchased a machine at a price of $90,000 on January 1, 2018. Online also paid $5,000 for installation and startup costs. Online also incurred some maintenance costs of $10,000 during 2018 . Online expects to be able to sell the machine for scrap parts for $15,000 at the end of the useful life. Assume straight-line depreciation for 2018 is $5,000. What is the expected useful life of the asset, in years