4, -11/12 + 5/6 <x/36< 7/9 - 3/4 5, 59/x = 11/4 + 13/6 6, x/15 = 3/4 + -17/20

Đáp án:

$\begin{array}{l}
4) - \dfrac{{11}}{{12}} + \dfrac{5}{6} < \dfrac{x}{{36}} < \dfrac{7}{9} - \dfrac{3}{4}\\
 \Leftrightarrow \dfrac{{ - 11.3 + 5.5}}{{36}} < \dfrac{x}{{36}} < \dfrac{{7.4 - 3.9}}{{36}}\\
 \Leftrightarrow \dfrac{{ - 8}}{{36}} < \dfrac{x}{{36}} < \dfrac{1}{{36}}\\
 \Leftrightarrow  - 8 < x < 1\\
Vậy\, - 8 < x < 1\\
5)Dk:x \ne 0\\
\dfrac{{59}}{x} = \dfrac{{11}}{4} + \dfrac{{13}}{6}\\
 \Leftrightarrow \dfrac{{59}}{x} = \dfrac{{11.3 + 13.2}}{{12}}\\
 \Leftrightarrow \dfrac{{59}}{x} = \dfrac{{59}}{{12}}\\
 \Leftrightarrow x = 12\left( {tm} \right)\\
Vậy\,x = 12\\
6)\dfrac{x}{{15}} = \dfrac{3}{4} + \dfrac{{ - 17}}{{20}}\\
 \Leftrightarrow \dfrac{x}{{15}} = \dfrac{{3.5 - 17}}{{20}}\\
 \Leftrightarrow \dfrac{x}{{15}} = \dfrac{{ - 2}}{{20}} =  - \dfrac{1}{{10}}\\
 \Leftrightarrow x =  - \dfrac{{15}}{{10}}\\
 \Leftrightarrow x =  - \dfrac{3}{2}\\
Vậy\,x =  - \dfrac{3}{2}
\end{array}$