Answer
$\color{blue}{x=4}$
Work Step by Step
RECALL:
A vertical line has an undefined slope and an equation of the form $x=h$ where $h$ is the x-intercept.
All points on the line have $x=h$.
The given line is vertical and contains the point $(4, -5)$.
This means that all points on the line have $x=4$, and that the equation of the line itself is $x=4$.
Thus, the equation of the line is:
$\color{blue}{x=4}$
