Intermediate Algebra (6th Edition)

$m=0$
Using the properties of equality, the given equation, $y-3=0 ,$ is equivalent to \begin{array}{l} y=3 .\end{array} All linear equations of the form $y=b$, where $b$ is any real number, have a slope of $0$. Hence, the slope of the given equation is $m=0 .$