Machinery is purchased on July 1 of the current fiscal year for $240,000. It is expected to have a useful life of 4 years, or 25,000 operating hours, and a residual value of $15,000.

Compute the depreciation for the last six months of the current fiscal year ending December 31 by each of the following methods:

a. Straight-line $

b. Double-declining-balance $

c. Units-of-output (used for 1,600 hours during the current year) $