I have the Math textbooks and answer keys for 2nd and 3rd year of junior high school, purchased from Mabuchi Kobetsu for exam preparation (approximately 1600 yen). I also have the Selected Training textbook and answer key for 3rd year (approximately 3000 yen). Some problems have been solved, and I wrote my name in the answer key. The friends around me who used these textbooks went on to high schools with high academic standards. I neglected them, so they have been stored almost new...