Ответ:

№65

3) (7/15+2/9)-2/15=7/15+2/9-2/15=5/15+2/9=1/3+2/9=3/9+2/9=5/9

4) 14/27-(5/27+1/6)=14/27-5/27-1/6=1/6

   14/27-5/27=9/27=1/3

   1/3-1/6=2/6-1/6=1/6

Verified answer

Пошаговое объяснение:

№3

1) 7/15 + 2/9 = 21/45 + 10/45 = 31/45

2) 31/45 - 2/15 = 31/45 - 6/45 = 25/45 = 5/9

№4

1) 5/27 + 1/6 = 10/54 + 9/54 = 19/54

2) 14/27 - 19/54 = 28/54 - 19/54 = 9/54 = 1/6