Subtract $6x$ from both sides.

$\begin{array}{l} \quad 4x=6x-14\\ \; -6x \; -6x\\ \; −2x = −14 \end{array}$

Divide each side by $-2$.

$\frac{-2x}{-2}=\frac{-14}{-2}$

$x=7$

Try using the same method presented in part (a).