Kansas Enterprises purchased equipment for $60,000 on January 1, 2012. The equipment is expected to have a five-year life, with a residual value of $5,000 at the end of five years. Using the double-declining balance method, the book value at December 31, 2013 would be: a. $21,600. b. $24,800. c. $36,000. d. $45,600.