\(x:\dfrac{3}{7}=\dfrac{1}{5}+\dfrac{2}{5}\)
\(x:\dfrac{3}{7}=\dfrac{3}{5}\)
\(x=\dfrac{3}{5}\times\dfrac{3}{7}\)
\(x=\dfrac{9}{35}\)
\(x:\dfrac{3}{7}=\dfrac{1}{5}+\dfrac{2}{5}\)
\(\Leftrightarrow x:\dfrac{3}{7}=\dfrac{3}{5}\)
\(\Leftrightarrow x=\dfrac{3}{5}\times\dfrac{3}{7}\)
\(\Leftrightarrow x=\dfrac{9}{35}\)