Ответ:

1) 5/18 + 4/18 = (5+4)/18 = 9/18 = 1/2

2) 25/34 - 8/34 = (25-8)/34 = 17/34 = 1/2

3) 3 13/45 + 6 17/45 = (3+6) + (13/45 + 17/45) = 9 + 30/45 = 9 + 2/3 = 9 2/3

4) 12 43/56 - 7 22/56 = (12 - 7) + (43/56 - 22/56) = 5 + 21/56 = 5 + 3/8 = 5 3/8

Ответ: 1) 1/2; 2) 1/2; 3) 9 2/3; 4) 5 3/8