Tìm x biết rằng: \(\frac{{ - 5}}{{ - 14}} = \frac{{20}}{{6 - 5x}}\)

* Hướng dẫn giải

Ta có:

 \(\begin{array}{l} \frac{{ - 5}}{{ - 14}} = \frac{{( - 5).( - 4)}}{{( - 14).( - 4)}} = \frac{{20}}{{56}} = \frac{{20}}{{6 - 5x}}\\ \Leftrightarrow 56 = 6 - 5x\\ \Leftrightarrow 56 - 6 = - 5x\\ \Leftrightarrow x = 50:( - 5)\\ \Leftrightarrow x = - 10 \end{array}\)