With the same Denominator
2/10 + 3/10 =
5/9 + 6/9 =
1/8 + 3/8 + 2/8=
5/13 + 2/13 + 3/13 =
4/9 + 12/9 =
7/10 - 2/10 =
11/15 - 6/15 =
8/16 - 8/16 =
8/12 - 3/12 - 1/12 =
15/20 - 7/20 - 2/20 =