Refer to the image below for the graph.
Work Step by Step
Subtract 12 on both sides of the equation to obtain: $3x=-12$ Divide 3 on both sides to obtain: $x=-4$ RECALL: (1) The graph of the equation $x=h$ is a vertical line whose x-intercept is $h$. (2) The graph of the equation $y=k$ or $f(x) =k$ is a horizontal line whose y-intercept is $k$. The equation above is similar to the form in (1) above. Thus, its graph is a vertical line whose x-intercept is $-4$. (refer to the attached image in the answer part above for the graph)