Ответ:

Пошаговое объяснение:

1) 5/6* 6/7 = (5*6)/(6*7) =  5/7

2) 2/9*1/2 = (2*1)/(9*2) = 1/9

3) 3/10*5/7 = (3*5)/(10*7) = 3/14

4) 7/10*9/14 = (7*9)/(10*14) = 9/20

5) 5/12*2/3 = (5*2)/(12*3) = 5/18

Ответ: 1) = 5/7

2) = 1/9

3) = 3/14

4) = 9/20

5) =5/18