[Used] This book allows you to master vector solutions through exercises and advanced exercises. There are date and check marks written on a few pages. I've flipped through it, and it doesn't seem like there are any writings that would affect solving the problems. There is one place highlighted with an orange marker. p31 - Title: Unit Mastery Vector Solution Patterns 30 - Publisher: Gijutsu Hyohronsha - Contents: Answers and explanations for exercises and advanced exercises Please refrain from cancellations or complaints after purchase. Thank you for looking.