a)

$\left|11x-33\right|-\left|2x-6\right|=27$  

$11\left|x-3\right|-2\left|x-3\right|=27$  

$9\left|x-3\right|=27$  

$\left|x-3\right|=3$  

$x-3=3\text{lub}x-3=-3$  

$x=6\text{lub}x=0$  

$x\in \left\{0,6\right\}$

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b)

$\left|x-6\right|+\left|4x-24\right|+\left|2x-12\right|=7$  

$\left|x-6\right|+4\left|x-6\right|+2\left|x-6\right|=7$  

$7\left|x-6\right|=7$  

$\left|x-6\right|=1$  

$x-6=1\text{lub}x-6=-1$  

$x=7\text{lub}x=5$

$x\in \left\{5,7\right\}$