Answer
$x=-2$
Work Step by Step
RECALL:
(1) For the point $(x, y)$, the x-coordinate represents the distance of the point from the y-axis.
(2) The equation of a vertical line is $x=h$ where $h$ is a real number.
The y-axis is a vertical line.
Thus, a line parallel to the y-axis is also a vertical line, which means that all points on the line have the same x-coordinate.
The line passes through the point $(-2, 7)$. The x-coordinate of this point is $-2$.
Thus, the equation of the line parallel to the y-axis that passes through the point $(-2, 7)$ is $x=-2$.