Ответ:

2/13×1/2=2/26=1/13

1/3×10/11=10/33

1/2×8/13=8/26=4/13

2/3×1/2=2/6=1/3

2/3×2/11=4/33

2/5×6/7=12/42=2/7

1/2×1/3=1/6

2/3×2/7=4/21

5/13×8/11=40/143

2/5×1/2=2/10=1/5

1/2×7/11=7/22

2/7×5/7=10/49

2/11×2/13=4/143

6/7×2/7=12/49

Ответ:

1:2/26

2:10/33

3:8/26

4:2/6