(х - 4) · 7 = 4 · (х + 3)
7х - 28 = 4х + 12
7х - 4х = 12 + 28
3х = 40
х = 40/3
х = 13 целых 1/3
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Проверка: (13 1/3 - 4) · 7 = 4 · (13 1/3 + 3)
9 1/3 · 7 = 4 · 16 1/3
28/3 · 7 = 4 · 49/3
196/3 = 196/3