a, \(x-\frac{1}{5}-\frac{2}{7}=4\frac{1}{2}\)
\(\Leftrightarrow x-\frac{17}{35}=\frac{9}{2}\)
\(\Leftrightarrow x=\frac{9}{2}+\frac{17}{35}\)
\(\Leftrightarrow x=\frac{349}{70}\)
b, \(1\frac{3}{4}+x-\frac{7}{8}=5\)
\(\Leftrightarrow\frac{7}{4}+x-\frac{7}{8}=5\)
\(\Leftrightarrow\frac{7}{8}+x=5\)
\(\Leftrightarrow x=5-\frac{7}{8}\)
\(\Leftrightarrow x=\frac{33}{8}\)