Giải chi tiết giúp mình nnha >3 Cảm ơn trước :33

Giải thích các bước giải:

$\begin{array}{l} a)\dfrac{4}{{15}} < \dfrac{x}{{30}} < \dfrac{1}{3}\\ \Rightarrow \dfrac{8}{{30}} < \dfrac{x}{{30}} < \dfrac{{10}}{{30}}\\ \Rightarrow 8 < x < 10\\ \Rightarrow x = 9\\ b)\dfrac{{ - 5}}{{12}} < \dfrac{x}{9} < \dfrac{2}{{ - 9}}\\ \Rightarrow \dfrac{{ - 15}}{{36}} < \dfrac{{4x}}{{36}} < \dfrac{{ - 8}}{{36}}\\ \Rightarrow - 15 < 4x < - 8\\ \Rightarrow - 3,75 < x < - 2\\ \Rightarrow x = - 3\\ c)\dfrac{3}{8} < \dfrac{x}{4} < \dfrac{3}{4}\\ \Rightarrow \dfrac{3}{8} < \dfrac{{2x}}{8} < \dfrac{6}{8}\\ \Rightarrow 3 < 2x < 6\\ \Rightarrow 1,5 < x < 3\\ \Rightarrow x = 2\\ d)\dfrac{5}{{12}} < \dfrac{{x + 1}}{6} < \dfrac{3}{4}\\ \Rightarrow \dfrac{5}{{12}} < \dfrac{{2(x + 1)}}{{12}} < \dfrac{9}{{12}}\\ \Rightarrow 5 < 2(x + 1) < 9\\ \Rightarrow 2,5 < x + 1 < 4,5\\ \Rightarrow 1,5 < x < 3,5\\ \Rightarrow x = 2\\ e)\dfrac{{ - 11}}{{12}} < \dfrac{x}{6} \le \dfrac{1}{{ - 2}}\\ \Rightarrow \dfrac{{ - 11}}{{12}} < \dfrac{{2x}}{{12}} \le \dfrac{{ - 6}}{{12}}\\ \Rightarrow - 11 < 2x \le - 6\\ \Rightarrow - 5,5 < x \le - 3\\ \Rightarrow x \in \left\{ { -5;- 4; - 3} \right\} \end{array}$