Verified answer

1) 3 1/8 + 7 5/12 + 5 3/8 + 1/12 = 3 1/8 + 5 3/8 + 7 5/12 + 1/12 = 8 4/8 + 7 6/12 = 8 1/2 + 7 1/2 = 15 2/2 = 16

2) 10 2/5 + 15 5/6 + 3 3/5 + 4 1/6 = 10 2/5 + 3 3/5 + 15 5/6 + 4 1/6 = 13 5/5 + 19 6/6 = 14 + 20 = 34

3) 9 7/8 + 5 2/7 + 1 1/8 + 4 5/7 = 9 7/8 + 1 1/8 + 5 2/7 + 4 5/7 = 10 8/8 + 9 7/7 = 11 + 10 = 21

4) 15 7/18 + 11 8/9 + 4/9 + 5/18 = 15 7/18 + 5/18 + 11 8/9 + 4/9 = 20 12/18 + 11 12/9 = 20 6/9 + 13 3/9 = 20 2/3 + 13 1/3 = 33 3/3 = 34