Odpowiedź :
7/14 + 17/21 = 3,5/7 + 17/21 = 10,5/21 + 17/21 = 27,5/21 = 1 i 6,5/21
2/5 + 11/15 = 6/15 + 11/15 = 17/15 = 1 2/15
3/4 + 11/16 = 12/16 + 11/16 = 23/16 = 1 i 7/16
8/9 + 4/7 = 56/63 + 36/63 = 92/63 = 1 i 29/63
7/14 + 17/21 = 3,5/7 + 17/21 = 10,5/21 + 17/21 = 27,5/21 = 1 i 6,5/21
2/5 + 11/15 = 6/15 + 11/15 = 17/15 = 1 2/15
3/4 + 11/16 = 12/16 + 11/16 = 23/16 = 1 i 7/16
8/9 + 4/7 = 56/63 + 36/63 = 92/63 = 1 i 29/63