1a. $3x$-$7$ = $\frac{1}{2}$
$3x$ = $\frac{1}{2}$ +$7$
$3x$ = $\frac{15}{2}$
⇒ $x$ = $\frac{5}{2}$
b. $\frac{27}{x}$ =$\frac{3.6}{-2}$
$\frac{27}{x}$ =$\frac{18}{-2}$
$\frac{27}{x}$ =$-9$
$27$ : x = $-9$
$x$ = $-3$
c.$|x-10|$ = $2015$
⇒\(\left[ \begin{array}{l}x-10=2015\\x-10=-2015\end{array} \right.\)
⇒\(\left[ \begin{array}{l}x=2025\\x=-2005\end{array} \right.\)
$Vậy$ $x$ $∈$ {$ 2025 , -2005$}
2 . $12$.($-5$) =$(-3)$.$20$
⇒ $\frac{12}{-3}$ =$\frac{20}{-5}$ ,$\frac{12}{20}$ =$\frac{-3}{-5}$ ,$\frac{-5}{-3}$ =$\frac{20}{12}$ ,$\frac{-5}{20}$ =$\frac{-3}{12}$
$vuatoanhoc$
