a) \(11+x=-12\)
\(\Leftrightarrow x=-12-11\)
\(\Leftrightarrow x=-23\)
b) \(2-x=17-\left(-5\right)\)
\(\Leftrightarrow2-x=17+5\)
\(\Leftrightarrow2-x=22\)
\(\Leftrightarrow x=2-22\)
\(\Leftrightarrow x=-20\)
c) \(x-12=\left(-9\right)-15\)
\(\Leftrightarrow x-12=-24\)
\(\Leftrightarrow x=-24+12\)
\(\Leftrightarrow x=-12\)
d) \(\left|x\right|-7=9\)
\(\Leftrightarrow\left|x\right|=9+7=16\)
\(\Rightarrow\left[{}\begin{matrix}x=16\\x=-16\end{matrix}\right.\)
e) \(9-25=\left(7-x\right)-\left(25+7\right)\)
\(\Leftrightarrow-16=\left(7-x\right)-32\)
\(\Leftrightarrow-16+32=7-x\)
\(\Leftrightarrow16=7-x\)
\(\Leftrightarrow x=7-16=-9\)
