Find a place where the line meets a cross section (corner of a box, where two graph lines meet) on the graph
I'm looking at -3, -3
Then we go straight up the graph on -3 until the line meets an other one of those cross sections. It does this at 0, -2. Count or add up how far we moved.
We're going to count over how far that is from where we are from the last step. You should have made a little triangle with the two graph lines and our blue line if you were to draw what we just did.
We moved up 3 and over 1 to get from the first cross section to the second. You can do this at any cross section on the graph that the blue line touches.
