2 câu trả lời
$ĐKXĐ:x\neq 0$
$\dfrac{10}{x}+12(\dfrac{1}{80}-\dfrac{1}{x})=\dfrac{2}{15}$
$⇔\dfrac{10}{x}+\dfrac{12}{80}-\dfrac{12}{x}=\dfrac{2}{15}$
$⇔\dfrac{10}{x}+\dfrac{3}{20}-\dfrac{12}{x}=\dfrac{2}{15}$
$⇔\dfrac{-2}{x}+\dfrac{3}{20}=\dfrac{2}{15}$
$⇔\dfrac{-2}{x}=\dfrac{-1}{60}$
$⇔x=120$
Vậy `S={120}`