$\begin{array} { l }7=-\frac{ 4 }{ 3y-1 },& y≠\frac{ 1 }{ 3 }\end{array}$
$7\left( 3y-1 \right)=-4$
$21y-7=-4$
$21y=-4+7$
$21y=3$
$\begin{array} { l }y=\frac{ 1 }{ 7 },& y≠\frac{ 1 }{ 3 }\end{array}$
$\begin{align*}&y=\frac{ 1 }{ 7 } \\&\begin{array} { l }y=0.\overline{ 142857 },& y={7}^{-1}\end{array}\end{align*}$