304. Решите уравнение: a) 0,4 (6x - 7) = 0,5 (3x + 7); б) 7 (1,4у + 1,8) - 27,6 = 10,1y; в) (2 \frac{7}{9}z + 3 \frac{1}{3}) \frac{3}{5} = \frac{1}{6}z + 6 \frac{1}{2}.

a) \(0,4 (6x - 7) = 0,5 (3x + 7)\) \(2,4x - 2,8 = 1,5x + 3,5\) \(2,4x - 1,5x = 3,5 + 2,8\) \(0,9x = 6,3\) \(x = \frac{6,3}{0,9}\) \(x = 7\) Ответ: x = 7 б) \(7 (1,4y + 1,8) - 27,6 = 10,1y\) \(9,8y + 12,6 - 27,6 = 10,1y\) \(9,8y - 10,1y = 27,6 - 12,6\) \(-0,3y = 15\) \(y = \frac{15}{-0,3}\) \(y = -50\) Ответ: y = -50 в) \((2 \frac{7}{9}z + 3 \frac{1}{3}) \frac{3}{5} = \frac{1}{6}z + 6 \frac{1}{2}\) \((\frac{25}{9}z + \frac{10}{3}) \frac{3}{5} = \frac{1}{6}z + \frac{13}{2}\) \(\frac{25}{9}z \cdot \frac{3}{5} + \frac{10}{3} \cdot \frac{3}{5} = \frac{1}{6}z + \frac{13}{2}\) \(\frac{5}{3}z + 2 = \frac{1}{6}z + \frac{13}{2}\) \(\frac{5}{3}z - \frac{1}{6}z = \frac{13}{2} - 2\) \(\frac{10}{6}z - \frac{1}{6}z = \frac{13}{2} - \frac{4}{2}\) \(\frac{9}{6}z = \frac{9}{2}\) \(\frac{3}{2}z = \frac{9}{2}\) \(z = \frac{9}{2} \cdot \frac{2}{3}\) \(z = 3\) Ответ: z = 3