Пошаговое объяснение:

Ответ:

1) 5/12-2/9 = 5/12(3)-2/9(4) = 15/36-8/36 = 7/36

2) 9/14+1/6 = 9/14(3)+1/6(7) = 27/42+7/42 = 34/42 = 17/21

3) 9/14-1/6 = 9/14(3)+1/6(7) = 27/42+7/42 = 20/42 = 10/21

4) точно такая же

5) 1/4+1/6 = 1/4(3)+1/6(2) = 3/12+2/12 = 5/12

6) 1/4-1/6 = 1/4(3)-1/6(2) = 3/12-2/12 = 1/12