Draw the graphs of linear equations $y=x$ and $y=-x$ on the same Cartesian plane.
What do you observe?

(N/A) Any point on the graph of $y = x$ will have $x$ and $y$ coordinates that are identical. The line passes through the points $(0,0), (1,1),$ and $(-1,-1).$
Similarly,any point on the graph of $y = -x$ will have $x$ and $y$ coordinates of opposite signs. The line passes through the points $(1,-1)$ and $(-1,1).$
Also,the point $(0,0)$ satisfies the equation $y = -x.$
The graphs of the linear equations $y = x$ and $y = -x$ on the same Cartesian plane are shown in the figure below.
We observe that the graphs of both these equations intersect at the origin $(0,0).$