Выполните вычетание:
1/3-1/9;10/21-1/3;14/15-3/5;17/18-1/9;4/9-13/45;1/3-7/30:

1/3-1/9=3/9 - 1/9 = 2/9;10/21-1/3=10/21 - 7/21 = 3/21 = 1/7;14/15-3/5=14/15 - 9/15 = 5/15 = 1/3;17/18-1/9=17/18 - 2/18 = 15/18 = 5/6;4/9-13/45=20/45 - 13/45 = 7/45;1/3-7/30=10/30 - 7/30 = 3/30 = 1/10