At December 31, the unadjusted trial balance of H&R Tacks reports Unearned Revenue of $4,000 and Service Revenues of $32,800. One-half of the unearned revenue has been earned as of December 31 1. Prepare the adjusting journal entry on December 31. (If no entry is required for a transaction/event, select "No Journal Entry Required" in the first account field.)