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 + 8 6/12 =
= 8 1/2 + 8 1/2 = 1
= 6 2/2 =17,
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) =
= 15 12/18 + 11 12/9 =
= 15 2/3 + 11 3/9 =
= 15 2/3 + 11 1/3 =
= 26 3/3 = 27