3-7/12 6-4/2/9 2/7/11+1/6/11 3/14+2/5/6 8,2-3,7+2/4/25

Ну что-то так: -12
22/7+11/6=209/42
3/14+12/5=183/70
4,5+50/4=17

3 - 7/12 = 36/12-7/12=29/12=2 5/12, 6 - 4 2/9 = 54/9-38/9=16/9=1 7/9, 2 7/11 + 1 6/11 = 29/11+17/11=46/11 = 4 2/11, 3/14 + 2 5/6 = 3/14 + 17/6 = 9/42+119/42=128/42= 3 2/42 = 3 1/21, 8,2 - 3,7 + 2 4/25 = 4,5 + 2,16 = 6,66