Draw the graph of the equation represented by a straight line which is parallel to the $x$-axis and at a distance $3$ units below it.

(N/A) The equation of a line parallel to the $x$-axis at a distance $a$ units below it is given by $y = -a$.
Here,the distance is $3$ units below the $x$-axis,so $a = 3$.
Therefore,the equation of the line is $y = -3$.
This line is parallel to the $x$-axis and passes through every point where the $y$-coordinate is $-3$,such as $(0, -3)$,$(1, -3)$,$(-1, -3)$,etc.
The graph of the equation $y = -3$ is a horizontal line passing through the point $(0, -3)$ on the $y$-axis,as shown in the figure.