Hãy tìm x biết \(\begin{array}{r} \frac{3}{7}-\frac{4}{7}:(x-1)=\frac{5}{7} \end{array}\)

* Hướng dẫn giải

 \(\begin{array}{r} \frac{3}{7}-\frac{4}{7}:(x-1)=\frac{5}{7} \\ -\frac{4}{7}:(x-1)=\frac{5}{7}-\frac{3}{7} \end{array}\)

\(\begin{aligned} &-\frac{4}{7}:(x-1)=\frac{2}{7} \\ &x-1=-\frac{4}{7}: \frac{2}{7}=-2 \\ &x=-2+1=-1 \\ &\text { Vậy } x=-1 \end{aligned}\)