Ответы:

1) (8/5 + 9/5) · 1/2; 17/5 · 1/2 = 17/10.

2) (6 - 68/15) : 11/5; 22/15 · 5/11 = 2/3.

3) (5/4 + 1/6) · 12/5; 17/12 · 12/5 (сокращаем); 17 · 1/5 = 17/5.

4) (27/5 - 7/3) : 23/3; 46/15 · 3/23 = 2/5.

5) (7/3 + 1/4) · 3/25; 31/12 · 3/25 (сокращаем); 31/4 · 1/25 = 0.31.

6) (38/5 - 19/4) : 19/10; 57/20 · 10/19 = 3/2.