I used this when I was taking university entrance exams. While I have written in it and solved the exercises, the condition of the product is quite good, with no folds or tears. This book is structured with video lessons, key point summaries, Q&A, and practice problems, so please note that only the practice problems are unusable. Therefore, I would appreciate it if you could use the book in conjunction with another text for the practice problems. As a result, I have significantly reduced the price from the original retail price. Thank you.