Пошаговое объяснение:
7 7/30-(5 11/30-у) =3 19/30
7 7/30 = (7*30+7)/30 = 217/30
5 11/30 = (5*30+11)/30 = 161/30
3 19/30 = (3*30+19)/30 = 109/30
217/30 – (161/30 – у) = 109/30
217/30 – 161/30 + у = 109/30
у = 109/30 - 217/30 + 161/30
у = (109 – 217 + 161)/30 = 53/30 = 1 23/30
