Tìm số nguyên x, biết 

- Hướng dẫn giải

$\begin{array}{l}\frac{1}{6}-\frac{2}{5}<\frac{x}{30}\le \frac{1}{2}-\frac{8}{15}\\ \Rightarrow \frac{5}{30}-\frac{12}{30}<\frac{x}{30}\le \frac{15}{30}-\frac{16}{30}\\ \Rightarrow \frac{-7}{30}<\frac{x}{30}\le \frac{-1}{30}\\ \Rightarrow -7<x\le -1\\ \Rightarrow x\in \left\{-6;-5;-4;-3;-2;-1\right\}\end{array}$