toán lớp 7 tìm x 2/3-(-1/2-x)=-4/5

Lời giải:

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

⇔\(\left( { - \frac{1}{2} - x} \right) = - \frac{4}{5} - \frac{2}{3}\)

⇔\( - \frac{1}{2} - x = - \frac{{22}}{{15}}\)

⇔\(x = - \frac{1}{2} - \left( { - \frac{{22}}{{15}}} \right)\)

⇔\(x = - \frac{1}{2} + \frac{{22}}{{15}}\)

⇔\(x = \frac{{29}}{{30}}\)

Vậy \(x = \frac{{29}}{{30}}\)