Set of 3 learning textbooks from the Red Navi series, with answer keys and explanations. - Subject: Social Studies - Subject: Science - Subject: English My high school sophomore son used these for exam preparation. These are advanced problem sets recommended by his school. There are no markings in the English and Social Studies books. There is one instance of writing in the Science book. I apologize if I missed any other markings. He studied with them to a certain extent, so there are some creases on the covers, but the inside is clean. Although it will be more expensive, I am open to selling them individually. Would you like these for your skills tests or exam preparation? Thank you for looking.