a) Ta có: \(71+\frac{26-3x}{5}=75\)
\(\Leftrightarrow\frac{26-3x}{5}=4\)
\(\Leftrightarrow26-3x=20\)
\(\Leftrightarrow3x=6\)
hay x=2
Vậy: x=2
b) Ta có: \(\left|x-12\right|=5\)
\(\Leftrightarrow\left[{}\begin{matrix}x-12=5\\x-12=-5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=17\\x=-5+12=7\end{matrix}\right.\)
Vậy: \(x\in\left\{17;7\right\}\)
c) Ta có: \(\frac{7}{8}+x=\frac{3}{5}\)
\(\Leftrightarrow x=\frac{3}{5}-\frac{7}{8}\)
\(\Leftrightarrow x=\frac{24}{40}-\frac{35}{40}\)
hay \(x=-\frac{11}{40}\)
Vậy: \(x=-\frac{11}{40}\)
d) Ta có: \(\frac{1}{2}x-\frac{2}{5}=\frac{1}{5}\)
\(\Leftrightarrow\frac{1}{2}\cdot x=\frac{1}{5}+\frac{2}{5}=\frac{3}{5}\)
\(\Leftrightarrow x=\frac{3}{5}:\frac{1}{2}=\frac{3}{5}\cdot2\)
hay \(x=\frac{6}{5}\)
Vậy: \(x=\frac{6}{5}\)
