5.100 Решите уравнение: a) 0,7x + 4 = 0,3x; б) -0,2x - 18 = 0,7x; в) 2х 1 3- = x + 2

a)

\[0.7x + 4 = 0.3x\]

\[0.7x - 0.3x = -4\]

\[0.4x = -4\]

\[x = \frac{-4}{0.4}\]

\[x = -10\]

Ответ: x = -10

б)

\[-0.2x - 18 = 0.7x\]

\[-0.2x - 0.7x = 18\]

\[-0.9x = 18\]

\[x = \frac{18}{-0.9}\]

\[x = -20\]

Ответ: x = -20

в)

\[2x - 3\frac{1}{3} = \frac{5}{6}x + 2\frac{1}{2}\]

\[2x - \frac{10}{3} = \frac{5}{6}x + \frac{5}{2}\]

\[2x - \frac{5}{6}x = \frac{5}{2} + \frac{10}{3}\]

\[\frac{12x - 5x}{6} = \frac{15 + 20}{6}\]

\[\frac{7}{6}x = \frac{35}{6}\]

\[x = \frac{35}{6} \cdot \frac{6}{7}\]

\[x = \frac{35}{7}\]

\[x = 5\]

Ответ: x = 5