5/6 +(2-1,23/35):9/25-1,2/7

5/6 + (2 - 1 23/35) : 9/25 - 1 2/7 = 1/2

1) 2 - 1 23/35 = 1 35/35 - 1 23/35 = 12/35

2) 12/35 : 9/25 = 12/35 · 25/9 = (4·5)/(7·3) = 20/21

3) 5/6 + 20/21 = 35/42 + 40/42 = 75/42 = 25/14 = 1 11/14

4) 1 11/14 - 1 2/7 = 1 11/14 - 1 4/14 = 7/14 = 1/2 (сократили на 7)

ответ: 1/2.