1)
3/12 + 25/30 = 1/4 + 5/6 = 3/12 + 10/12 = 13/12 = 1 1/12,
2)
10/24 - 21/54 = 5/12 - 7/18 = 15/36 - 14/36 = 1/36,
3)
30/54 + 22/30 = 5/9 + 11/15 = 25/45 + 33/45 = 58/45 = 1 13/45,
4)
28/40 - 10/75 = 7/10 - 2/15 = 21/30 - 4/30 = 17/30,
5)
12/27 + 14/21 = 4/9 + 2/3 = 4/9 + 6/9 = 10/9 = 1 1/9,
6)
14/24 - 15/40 = 7/12 - 3/8 = 14/24 - 9/24 = 5/24,
7)
12/18 - 5/60 = 2/3 - 1/12 = 8/12 - 1/12 = 7/12,
8)
4/24 + 3/36 = 1/6 + 1/12 = 2/12 + 1/12 = 3/12 = 1/4