Tìm x , biết: (a) 2 x − 5 /6 = − 7 /8

Tìm \[x\], biết:

(a) \(2x - \frac{5}{6} = - \frac{7}{8}\)

(b) \({\left( {x:\frac{2}{3} + \frac{4}{5}} \right)^2} = \frac{4}{{25}}\).