#### Answer

$x=\left\{-1, 7\right\}$
Refer to the image below for the graph.

#### Work Step by Step

To solve the given equation graphically, perform the following steps:
(1) Let each side of the equation represent a function then graph each function on the same coordinate plane.
Graph $y=x^2-4x$ (the blue graph) and $y=2x+7$ (the red graph).
(refer to the attached image in the answer part above for the graph)
(2) Identify the point/s where the two graphs intersect. The x-coordinate of point of intersection is a solution of the given equation.
The graphs intersect at $(-1, 5)$ and $(7, 21)$.
Therefore, the solutions to the given equation are:
$x=\left\{-1, 7\right\}$