Eager Co. receives $20,000 cash in advance for 4 months of legal services on October 1, 2011, and records it by debiting Cash and crediting Unearned Revenue both for $20,000. It is now December 31, 2011, and Eager has provided legal services as planned. What adjusting entry should Eager make to account for the work performed from October 1 through December 31, 2011?