\(a.\)
\(x+\frac{3}{7}=0\)
\(\Rightarrow x=0-\frac{3}{7}\)
\(\Rightarrow x=-\frac{3}{7}\)
Vậy : \(x=-\frac{3}{7}\)
\(b.\)
\(3x+\frac{3}{5}=0\)
\(\Rightarrow3x=0+\frac{3}{5}\)
\(\Rightarrow3x=\frac{3}{5}\)
\(\Rightarrow x=\frac{3}{5}:3\)
\(\Rightarrow x=\frac{3}{5}.\frac{1}{3}\)
\(\Rightarrow x=\frac{1}{5}\)
Vậy : \(x=\frac{1}{5}\)