Where do the lines intersect?

They are intersecting at 0,0.
One square on that chart is 2 units.
You can see this since it goes -10 then skips one then goes to -6.
The one in between is -8.
On every side of the intersection there is a 2 or -2.
2 - 2 or -2 + 2, depending if it's positive or negative, is 0.
So the lines are intersecting at 0,0.
Hope this helps! :)

I'd say -5