Answer
Refer to the image below for the graph.
Work Step by Step
Divide 7 on both sides of the equation to obtain:
$y=-\frac{21}{7}$
$\\y=-3$
RECALL:
The graph of an equation of the form $y=k$ is a horizontal line whose y-intercept is $k$.
The given equation has $k=-3$ therefore its graph is a horizontal line whose y-intercept is $-3$.
The points on the line share the same y-value of $-3$.
This means that the line contains the points $(-2, -3)$, $(0, -3)$, and $(2, -3)$.
To graph $y=-3$, plot the three points then connect them using a line.
(refer to the attached image in the answer part for the graph)
