1) 3/4 - 1/6 = 9/12 - 2/12 = 7/12 7/12 + 1/2 = 7/12 + 6/12 = 13/12 = 1 1/12
2) 4/9 + 5/6 = 8/18 + 15/18 = 23/18 23/18 - 3/4 = 46/36 - 27/36 = 19/36
3) 4/15 - 2/45 = 12/45 - 2/45 = 10/45 10/45 + 7/9 = 10/45 + 35/45 = 45/45 = 1
4) 6/7 - 1/4 = 24/28 - 7/28 = 17/28 17/28 + 5/14 = 17/28 + 10/28 = 27/28
5) 7/10 + 9/14 = 49/70 + 45/70 = 94/70 95/70 - 3/35 = 95/70 - 6/70 = 89/70 = 1 19/70
6) 11/12 - 1/9 = 33/36 - 4/36 = 29/36 29/36 + 1/4 = 29/36 + 9/36 = 38/36 = 1 2/36 = 1 1/18
Надеюсь понятно)))