\(\dfrac{2\left(x-3\right)}{7}-x+2=\dfrac{13x+4}{21}\)
\(\Leftrightarrow\dfrac{2\left(x-3\right)}{7}-x+2=\dfrac{12x+1x+4}{21}\)
\(\text{}\Leftrightarrow\dfrac{2\left(x-3\right)}{7}-x+2=\dfrac{1x+3\left(4x+1\right)}{21}\)
\(\Leftrightarrow\dfrac{2\left(x-3\right)}{7}-x+2=\dfrac{5x+1}{7}\)
\(\Leftrightarrow\dfrac{2\left(x-3\right)}{7}-x=\dfrac{5x+1-14}{7}\)
\(\Leftrightarrow x=\dfrac{2x-6}{7}-\dfrac{5x+1-14}{7}\)
\(\Leftrightarrow x=\dfrac{2\left(x-3\right)}{7}-\dfrac{5\left(x+5\right)-1+1}{7}\)
\(\Leftrightarrow x=\dfrac{2\left(x-3\right)}{7}-\dfrac{3+2\left(x+3\right)+2}{7}\)
\(\Leftrightarrow x=\dfrac{-4}{7}\)