Odpowiedź:
1 - 1/9 = 9/9 - 1/9 = 8/9
7 - 1/9 = 6 i 9/9 - 1/9 = 6 i 8/9
10 - 1/9 = 9 i 9/9 - 1/9 = 9 i 8/9