This is a learning resource from the Gnoble Basic Mastery series, designed to thoroughly teach the fundamentals of arithmetic. - Title: Ratio - Title: Percentage - Title: Similarity - Title: Area Ratio - Title: Equivalent Calculation, Work Problems, and Multiple Problems - Title: Traveler Problems, Passing Problems, Time Problems, and River Flow Problems Thank you for viewing. This is a reference book purchased for basic skill reinforcement at Gnoble. Most of the books have a few pages with writing, one book is less than half-filled, and one book has no writing. Everything has been carefully erased with an eraser. Circles were marked with friction pens, so they have all been erased. However, some people may still find them visible depending on the viewing angle and lighting. There should be no problem if you copy the pages for use. Please understand that these are used items before purchasing. Returns are not accepted. All books come with answers. There is no writing in the answers.