a) $\dfrac{2}{\dfrac{31}{3}}:|x|=0,8$
$↔\dfrac{6}{31}:|x|=0,8$
$↔|x|=\dfrac{6}{31}:0,8$
$↔|x|=\dfrac{6}{31}.\dfrac{5}{4}$
$↔|x|=\dfrac{15}{62}$
\(↔\left[ \begin{array}{l}x=\dfrac{15}{62}\\x=-\dfrac{15}{62}\end{array} \right.\)
b) $11-|1-3x|=6$
$↔|1-3x|=11-6=5$
\(↔\left[ \begin{array}{l}1-3x=5\\1-3x=-5\end{array} \right.\)
\(↔\left[ \begin{array}{l}3x=-4\\3x=6\end{array} \right.\)
\(↔\left[ \begin{array}{l}x=-\dfrac{4}{3}\\x=2\end{array} \right.\)