(у + 5/7) · 1/3 = 2 4/9
(у + 5/7) · 1/3 = 22/9
у + 5/7 = 22/9 : 1/3
у + 5/7 = 22/9 · 3/1 = (22·1)/(3·1)
у + 5/7 = 22/3 = 7 1/3
у = 7 1/3 - 5/7 = 7 7/21 - 15/21 = 6 28/21 - 15/21 = 6 13/21
у = 6 целых 13/21
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Проверка: (6 13/21 + 5/7) · 1/3 = 2 4/9
(6 13/21 + 15/21) · 1/3 = 2 4/9
(6 28/21) · 1/3 = 2 4/9
154/21 · 1/3 = 2 4/9
154/63 = 22/9 = 2 4/9
