What line is perpendicular to y = -3 and passes through point (4, -6)?

$x = 4$
The line that is perpendicular to $y = - 3$ is a horizontal line, because horizontal and vertical lines ($x$- and $y$- axes for example) are perpendicular. Therefore, this line will take the form $x = n$ where $n$ is the $x$-coordinate of the point passed through. The $x$-coordinate of the given ordered pair $\left(4 , - 6\right)$ is $4$, so the equation must be $x = 4$