1. |a|=20
=>\(\left[ \begin{array}{l}a=20\\a=-20\end{array} \right.\)
2.|3b|=12
=>\(\left[ \begin{array}{l}3b=12\\3b=-12\end{array} \right.\)
=>\(\left[ \begin{array}{l}b=4\\b=-4\end{array} \right.\)
3. |a|-13=27
=>|a| = 40
=>\(\left[ \begin{array}{l}a=40\\a=-40\end{array} \right.\)
4. 2|b| -17 =35
=>2|b|=52
=>|b|=26
=>\(\left[ \begin{array}{l}a=26\\a=-26\end{array} \right.\)
5. |a+4| =19
=>\(\left[ \begin{array}{l}a+4=19\\a+4=-19\end{array} \right.\)
=>\(\left[ \begin{array}{l}a=15\\a=-23\end{array} \right.\)
