$x-13=\log_{ 6 }({ 7 })x$
Move the constant to the right-hand side and change its sign$x=\log_{ 6 }({ 7 })x+13$
Move the expression to the left-hand side and change its sign$x-\log_{ 6 }({ 7 })x=13$
Factor out $x$ from the expression$\left( 1-\log_{ 6 }({ 7 }) \right)x=13$
Divide both sides of the equation by $1-\log_{ 6 }({ 7 })$$\begin{align*}&x=\frac{ 13 }{ 1-\log_{ 6 }({ 7 }) } \\&x\approx-151.10458\end{align*}$