The equation for the best-fit function through the points on the graph below is y = 5x-1. We can tell from this equation and the graph that volume and pressure are __________.

I can tell that the graph is a straight line but that's all. With no graph, no labeled axes, and no knowledge of what is being on graphed, I'm at a loss. My best guess is that this is a pressure/volume relationship (just from th question) and I suspect that "pressure and volume are inversely proportional" is what goes in the blank. But that's just a best guess.