I have the Sūken Shuppan Mathematics II textbook and the 4-Step Process workbook. They can be sold separately (answers to the 4-Step Process workbook only are not available). If sold separately, both the textbook and the 4-Step Process workbook (with answers) are 300 yen each. The textbook has been used carefully and I didn't see any writing in it, but please be aware that I might have missed some. The 4-Step Process workbook has some "x" and check marks.