1) 3/7 - 1/6 = 18/42 - 7/42 = 11/42,
2) 5/9 - 2/7 = 35/63 - 18/63 = 17/63,
3) 3/4 - 1/3 = 9/12 - 4/12 = 5/12,
4) 2 3/5 - 1 1/4 = 13/5 - 5/4 = 52/20 - 25/20 = 27/20 = 1 7/20 (или
2 3/5 - 1 1/4 = (2 - 1) + (3/5 - 1/4) = 1 + (12/20 - 5/20) = 1 + 7/20 = 1 7/20),
5) 6 5/9 - 4 3/7 = 59/9 - 31/7 = 413/63 - 279/63 = 134/63 = 2 8/63 (или
6 5/9 - 4 3/7 = (6 - 4) + (5/9 - 3/7) = 2 + (35/63 - 27/63) = 2 + 8/63 = 2 8/63 ),
6) 8 - 5 5/7 = 56/7 - 40/7 = 16/7 = 2 2/7 (или
8 - 5 5/7 = (7 - 5) + (1 - 5/7) = 2 + (7/7 - 5/7) = 2 + 2/7 = 2 2/7 ),
7) 1 5/9 + 7/30 = 14/9 + 7/30 = 140/90 + 21/90 = 161/90 = 1 71/90,
8) 2 7/10 - 1 1/5 = 27/10 - 6/5 = 27/10 - 12/10 = 15/10 = 1 5/10 = 1 1/2