Videobusters, Incorporated offered books of video rental coupons to its patrons at $34 per book. Each book contained a certain number of coupons for video rentals. During the current period 440 books were sold for $14,960, and this amount was credited to Unearned Rental Revenue. At the end of the period, it was determined that 12,000 worth of coupons had been used by customers to rent videos. The appropriate adjusting entry at the end of the period would be: