Question

log_y (y-3x) = log_y (4)

Answer 1

$log_{y}(y-3x)=log_{y}(4)$
$y^{log_{y}(y-3x)} = y^{log_{y}(4)}$
$y-3x=4$
$-y+3x=-4$
$3x=y-4$
$x= \frac{y-4}{3}$