18. Falcon Corporation purchased a depreciable asset for $630,000 on January 1, 2012. The estimated salvage value is $63,000, and the estimated total useful life is 9 years. The straight-line method is used for depreciation. In 2015, Falcon changed its estimates to a useful life of 5 years with a salvage value of $105,000. What is 2015 depreciation expense? a. $63,000 b. $105,000 c. $168,000 d. $189,000