Two textbooks set. The red one is the main textbook and has chapter-end problems. It has been used, but there are no markings. The red and black one also has textbook elements, but it includes a "cramming ○× drill" and two sets of exam-style questions at the very end. I bought these textbooks this summer and passed the exam on the first try in about two months. They are easy to understand and I recommend them. Please consider them.