20. Cactus, Inc. purchased equipment for $720 on January 1, 2013. The equipment is expected to have a six-year life, with a residual value of $120 at the end of six years Using the straight-line method, depreciation expense for 2015 and the net book value at December 31,2015 would be A. $120 and $360 B. $100 and $420. C. $300 and $420. D. $100 and $300 E. None of the above