This is a problem set on angles and the properties of triangles. - Title: Arithmetic Basic 60 Problems 4 (Plane Figures 1) - Publisher: SAPIX I have used this book several times since I purchased it a few years ago. Out of a total of 68 pages, there are writings on pages 1 and 2, and eraser marks on pages 4-20. I have a cat. I remove any hair or dust before shipping, but I apologize if any remain. Therefore, I recommend that those with severe cat allergies refrain from purchasing. Thank you for looking.