Prepare the adjusting journal entries required on December 31 for Walker Corp. using the following information. Assume that no adjusting journal entries were recorded during the year prior to year-end. a. Interest expense of $180 for the month of December will be paid in January of next year. b. Unbilled revenue for services performed in December is $600. The company will prepare and forward invoices for this amount in January of next year to customers with a 30-day collection term. c. $1,800 cash was received in advance on November 30 for future services to be performed by Walker Corp. and was recorded as deferred service revenue. The services were performed on December 20. d. Walker Corp. acquired a two-year