a: Đề thiếu vế phải rồi bạn
b: \(\Leftrightarrow x\cdot\dfrac{-12}{13}=6+\dfrac{1}{13}+5=11+\dfrac{1}{13}=\dfrac{144}{13}\)
hay x=-12
c: \(\Leftrightarrow x\cdot\dfrac{-5}{4}-\dfrac{6}{5}x=\dfrac{-1}{2}-\dfrac{3}{7}\)
\(\Leftrightarrow x\cdot\dfrac{-49}{20}=\dfrac{-13}{14}\)
hay x=130/343