Đáp án+Giải thích các bước giải:
$a) -72x + 68 = 68 \\-72x=68-68\\-72x=0\\x=0:(-72)\\x=0$
$b) -35 - 78 : x = 74 \\78:x=-35-74\\78:x=(-109)\\x=78:(-109)\\x=-\dfrac{78}{109}$
`c) |x +99| - 39 = 44`$\\$`|x +99|=44+39`$\\$`|x +99|=83`$\\$`<=>`\(\left[ \begin{array}{l}x+99=83\\x+99=-83\end{array} \right.\) $\\$`<=>`\(\left[ \begin{array}{l}x=83-99\\x=-83-99\end{array} \right.\) $\\$`<=>`\(\left[ \begin{array}{l}x=-16\\x=-182\end{array} \right.\)
