(2/9+(-5/9))+2/3=3/9
1)2/9-5/9= - 3/9
2) -3/9+2/3=-3/9+6/9=3/9
1)2/9-5/9=-3/9 сокращаем на 3 и =-1/3
2)-1/3 +2/3=1/3
(2/9+(-5/9))+2/3=3/9
1)2/9-5/9= - 3/9
2) -3/9+2/3=-3/9+6/9=3/9
1)2/9-5/9=-3/9 сокращаем на 3 и =-1/3
2)-1/3 +2/3=1/3