7 7/30-(5 11/30-у)=3 19/30,
7 7/30- 5 11/30+у=3 19/30,
2 7/30-11/30+у=3 19/30,
67/30-11/30+у=3 19/30,
56/30+у=109/30,
у= 109/30-56/30,
у=53/30,
у=1 23/30
проверка
7 7/30-(5 11/30-1 23/30)= 3 19/30, 7 7/30-(4 11/30-23/30)= 3 19/30,
7 7/30-(131/30-23/30)=3 19/30, 217/30-108/30= 3 19/30, 109/30= 3 19/30, 3 19/30=3 19/30
-у=5 11/30-10 26/30
у=5 5/6
7 7/30-(5 11/30-у)=3 19/30,
7 7/30- 5 11/30+у=3 19/30,
2 7/30-11/30+у=3 19/30,
67/30-11/30+у=3 19/30,
56/30+у=109/30,
у= 109/30-56/30,
у=53/30,
у=1 23/30
проверка
7 7/30-(5 11/30-1 23/30)= 3 19/30, 7 7/30-(4 11/30-23/30)= 3 19/30,
7 7/30-(131/30-23/30)=3 19/30, 217/30-108/30= 3 19/30, 109/30= 3 19/30, 3 19/30=3 19/30