Ratio Tables: Moving to Generalisation

I have been raving about the utility of ratio tables for a couple of years now, and in my last MathsConf session I showed the versatility of them for topics across the curriculum. I ended with a snapshot of how I use them for algebraic direct proportion questions. People went a bit mad for it, and since then the biggest questions I have had have been about how to extend this idea, so I decided it was high time to share the specifics some more.