Thomas Book Sales Inc., supplies textbooks to college and university bookstores. The books are shipped with a proviso that they must be paid for within 30 days but can be returned for a full refund credit within 90 days. In 2009, Thomas shipped and billed book titles totaling $760,000. Collections, net of return credits, during the year totaled $690,000. The company spent $300,000, acquiring the books that it shipped.