Hãy tìm x biết ​\(\left( {x - \frac{3}{{14}}} \right):\frac{4}{{21}} = - \frac{3}{4}\)

* Hướng dẫn giải

 \(\begin{aligned} &\left( {x - \frac{3}{{14}}} \right):\frac{4}{{21}} = - \frac{3}{4}\\ &x - \frac{3}{{14}} = - \frac{3}{4}.\frac{4}{{21}}\\ &x - \frac{3}{{14}} = - \frac{1}{7}\\ &x = - \frac{1}{7} + \frac{3}{{14}}\\ &x = \frac{1}{{14}} \end{aligned}\)