Brainiac Company purchased a delivery truck for $30,000 on January 1, 2012. The truck has an expected salvage value of $2,000, and is expected to be driven 100,000 miles over its estimated useful life of 8 years. Actual miles driven were 15,000 in 2012 and 12,000 in 2013. Compute depreciation expense for 2012 and 2013 using (1) the straight-line method, (2) the units-of-activity method, and (3) the double-declining balance method