int itiwaribiki;
itiwaribiki = (int)(nedan * 0.9);

printf("一割引き＝%d\n", (int)(nedan * 0.9));
printf("一割引き＝%d\n", itiwaribiki);

printf("一割引き＝%d\n二割引き＝%d\n", (int)(nedan * 0.9), (int)(nedan * 0.8));