$a) 3-x=-5$
$⇔x=3+5$
$⇔x=8$
$b) 9-x=24-(-12)$
$⇔9-x=24+12$
$⇔x=9-24-12$
$⇔x=-27
$c) |x-4|=2$
$⇔\left[ \begin{array}{l}x-4=2\\x-4=-2\end{array} \right.$
$⇔\left[ \begin{array}{l}x=6\\x=2\end{array} \right.$
$d) 2|x-3|+5=9$
$⇔2|x-3|=9-5$
$⇔2|x-3|=4$
$⇔|x-3|=2$
$⇔\left[ \begin{array}{l}x-3=2\\x-3=-2\end{array} \right.$
$⇔\left[ \begin{array}{l}x=5\\x=1\end{array} \right.$
$e) (2x-12)+36=15+x$
$⇔2x-12+36-x-15-x=0$
$⇔x+9=0$
$⇔x=-9$
$f)5x-(-15)=50$
$⇔5x+15=50$
$⇔5x=35$
$⇔x=7$
$g) |x|-6=|-8|-2$
$⇔|x|-6=8-2$
$⇔|x|-6=6$
$⇔|x|=12$
$⇔x=\pm{12}$
$h) (-x+31)+33=-69$
$⇔-x+31+33=-69$
$⇔x=69+31+33$
$⇔x=133$
