Answer
$4$
Work Step by Step
RECALL:
The graph of an equation that is symmetric with respect to the y-axis has the following property:
If the point $(a, b) $ is on the graph of the equation, the point $(-a, b)$ is also on the graph of the equation.
Thus, if the graph of an equation that is symmetric with respect to the y-axis contains the point $(-4, 0)$ (x-intercept is $-4$), then its graph also contains the point $(4, 0)$.
Thus, $4$ is also an x-intercept of the graph.