Odpowiedź:
3/7 + 2/7 = 5/7
5/8 + 6/8 = 11/8 = 1 i 3/8
2 i 5/9 + 2/9 = 2 i 7/9
2 i 4/5 + 3 i 3/5 = 5 i 7/5 = 6 i 2/5
16/17 - 9/17 = 7/17
5 i 12/21 - 3 i 5/21 = 2 i 7/21 = 2 i 1/3
8 - 4/9 = 7 i 9/9 - 4/9 = 7 i 5/9
3 i 1/8 - 1 i 7/8 = 2 i 9/8 - 1 i 7/8 = 1 i 2/8 = 1 i 1/4
