3/4 - 1/4 = 2/4 = 1/2
5/8 + 3/8 = 8/8 = 1
7/12 - 5/12 = 2/12 = 1/6
8/15 + 2/15 = 10/15 = 2/3
3/10 + 1/10 = 4/10 = 2/5
17/25 - 12/25 = 5/25 = 1/5
1/30 + 7/30 = 8/30 = 4/15
28/45 - 13/45 = 15/45 = 1/3
3/4 - 1/4 = 2/4 = 1/2
5/8 + 3/8 = 8/8 = 1
7/12 - 5/12 = 2/12 = 1/6
8/15 + 2/15 = 10/15 = 2/3
3/10 + 1/10 = 4/10 = 2/5
17/25 - 12/25 = 5/25 = 1/5
1/30 + 7/30 = 8/30 = 4/15
28/45 - 13/45 = 15/45 = 1/3