Tìm x, biết:  a) x - 5/6 = - 7/6

a) \(x - \frac{5}{6} = \frac{{ - 7}}{6}\)

\(x = \frac{{ - 7}}{6} + \frac{5}{6}\)

\(x = \frac{{ - 2}}{6}\)

\(x = \frac{{ - 1}}{3}.\)

Vậy \(x = \frac{{ - 1}}{3}.\)

b) \(0,2 + 0,8:x = 0,15\)

\(0,8:x = 0,15 - 0,2\)

\(0,8:x = - 0,05\)

\(x = 0,8:\left( { - 0,05} \right)\)

\(x = - 16\)

Vậy \(x = - 16.\)

c) \(\frac{1}{3}:x + \left( { - \frac{3}{4} + \frac{2}{3}} \right):x = \frac{5}{8}\)

 \(\frac{1}{3} \cdot \frac{1}{x} - \frac{1}{{12}} \cdot \frac{1}{x} = \frac{5}{8}\)

 \(\left( {\frac{1}{3} - \frac{1}{{12}}} \right) \cdot \frac{1}{x} = \frac{5}{8}\)

 \(\frac{1}{4} \cdot \frac{1}{x} = \frac{5}{8}\)

 \(\frac{1}{x} = \frac{5}{2}\)

 \(x \cdot 5 = 1 \cdot 2\)

 \(5x = 2\)

     \(x = \frac{2}{5}\)

Vậy \(x = \frac{2}{5}.\)