1) 2 1/6 + 2 5/12 = 2 2/12 + 2 5/12 = 4 7/12
2) 5 1/10 + 8 3/8 = 5 4/40 + 8 15/40 = 13 19/40
3) 15 + 4 4/7 = 19 4/7
4) 23 2/10 - 20 1/10 = 3 1/10
5) 141 89/90 - 84 = 57 89/90
6) 2 7/9 - 1/3 = 2 7/9 - 3/9 = 2 4/9
7) 98 - 73 8/13 = 97 13/13 - 73 8/13 = 24 5/13
8) 1/5 * 3/7 = 3/35
9) 1 4/7 * 5 2/3 = 11/7 * 17/3 = 187/21 = 8 19/21
10) 4 * 1/7 = 4/1 * 1/7 = 4/7
11) 12 * 1 2/3 = 12/1 * 5/3 = 4/1 * 5/1 = 20
12) 4 2/5 * 4/7 = 22/5 * 4/7 = 88/35 = 2 18/35