4/7-2/7 =
8/10
12/12
2/6
6/10 + 2/10 =
9/11 - 7/11 =
14/9
9/9 + 5/9 =
6/6 - 4/6 =
2/7
4/12 + 8/12 =
6/8 + 5/8 =
11/8
2/11
