6/51 + 1/9 - 3/17
5/12 + 1/18 - 2/9
2/21 + 4/18 - 6/35
3/7 - (1/28 + 11/35)
5/8 + 1/6 - 7/12
13/30 - (2/45 + 1/9)

Пошаговое объяснение:

6/51 + 1/9 - 3/17 =18\153+17\153-27\153=8\153

5/12 + 1/18 - 2/9 =15\36+2\36-8\36=9\36=1\4

2/21 + 4/18 - 6/35 =60\630+140\630-108/630=92\630=46\315

3/7 - (1/28 + 11/35) =60\140-5\140-44\140=11\140

5/8 + 1/6 - 7/12 =15\24+4\24-14\24=5\24

13/30 - (2/45 + 1/9)=39\90-4\90-10\90=25\90=5\18