a,$\frac{-12}{13}$ .x-5=$\frac{79}{13}$
$\frac{-12}{13}$ .x =$\frac{79}{13}$ + 5
$\frac{-12}{13}$ .x =$\frac{144}{13}$
x = $\frac{144}{13}$ :$\frac{-12}{13}$
x =-12
Vậy x=-12
b.$\frac{3}{4}$ -(x+$\frac{1}{2}$ )=$\frac{4}{5}$
x+$\frac{1}{2}$ =$\frac{3}{4}$ -$\frac{4}{5}$ )
x+$\frac{1}{2}$ = $\frac{-1}{20}$
x = $\frac{-1}{20}$ - $\frac{1}{2}$
x = $\frac{-11}{20}$
Vậy x=$\frac{-11}{20}$
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