a) `2. |x-1| = 8`
`<=> |x-1| = 4`
`<=>` \(\left[ \begin{array}{l}x-1=4\\x-1=-4\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x=5\\x=-3\end{array} \right.\)
b) `|2-x| + 3/4 = 6,75`
`<=> |2-x| = 6`
<=>` \(\left[ \begin{array}{l}2-x=6\\2-x=-6\end{array} \right.\)
<=>` \(\left[ \begin{array}{l}x=-4\\x=8\end{array} \right.\)