1) 1 целая 5/15 - 6/15 = 14/15
2)23/4 + 9/4 = 46/4 + 9/4 =55\4 =13 целых 1/4
3)7/10+ 4/10 =11/10 =1 целая 1/10
4)2 целых 3/6+ 4/6 = 7/6 = 1 целая 1/6
5)16/6 -9/6 =7/6 = 1 целая 1/6
6)2 целых 9/21 - 1 целую 14/21 =16/21
7)1 целая 12/42 - 35/42 = 23/42