This is a 3-piece set consisting of a Math III textbook, a problem collection, and an explanation book. When you don't understand a wide-ranging problem, you can deepen your understanding by cross-referencing it with the textbook page on the right, which allows you to review the basic problems. As shown in the photos, some of the wide-ranging problems have circles marked on them. I believe there are no markings in the answer book or the textbook. The textbook has some pages that are slightly stuck together due to long-term sticky notes, but they can be easily removed and don't seem like they will tear. The textbook does not include answers to the problems. If you have any questions, please leave a comment.