Tìm x biết: a) x - 9/15 = -7/5 ;

* Hướng dẫn giải

$\begin{array}{l}\mathrm{a}) \mathrm{x}-\frac{9}{15}=\frac{-7}{5}\\ \mathrm{x}-\frac{3}{5}=\frac{-7}{5}\\ \mathrm{x}=\frac{3}{5}-\frac{7}{5}\\ \mathrm{x}=-\left(\frac{7}{5}-\frac{3}{5}\right)\\ \mathrm{x}=\frac{-4}{5}\\ \mathrm{Vậy} \mathrm{x}=\frac{-4}{5}\end{array}$