Plot points with coordinates where \(x\) and \(y\) are equal. Three points are sufficient, but more can be plotted. Draw a line through the plotted points. If \(x\) is positive, \(y\) is negative. If ...

I am not going to try and even surprise you with this. Notice the "tools:". This post is not about physics really, but something used in physics. When I get enough of these, I will put them together ...