Tìm x, biết: 2/3 + 7/4 :x = 5/6

a) \[\frac{2}{3} + \frac{7}{4}:x = \,\,\frac{5}{6}\]

\(\frac{7}{4}:x = \,\frac{5}{6} - \frac{2}{3}\)

\(\frac{7}{4}:x = \frac{1}{6}\)

\(x = \frac{7}{4}:\frac{1}{6}\)

\(x = \frac{{21}}{2}\)

Vậy \(x = \,\,\frac{{21}}{2}\)

 b) \[\frac{1}{4} - \left( {\frac{1}{4} + x} \right) = 0,25\]

\[\frac{1}{4} + x = \frac{1}{4} - 0,25\]

\[\frac{1}{4} + x = 0\]

\[x = \frac{{ - 1}}{4}\]

Vậy \[x = \frac{{ - 1}}{4}\]