These are all items I purchased on Mercari when I was taking my exams. The Akahon (red book) for Seijo University is fine for solving problems. The other two books may be a bit difficult to use, as they have ballpoint pen markings. I used correction fluid to erase the pen marks, so the inside condition isn't great. But you can still use them if you try! I'm selling all three, but if you only want one, please contact me.