Those are mathematical formulas that you plug numbers into to find the new conversion constant (which is defined in the first paragraph). Start at the bottom by going to Tire Rack to find the mfrs. Revs/mile for your particular tire, then plug that into the first equation (with 108 for "ToneRingTeeth) and voila! You get your conversion constant.

If your tire isn't listed, then you have to use the other formulas (starting at the bottom).

Every term is explained right there, so I still don't know what you're having trouble with. The formulas themselves are just algebra, using geometry & unit analysis, but you don't have to understand how they're derived to put numbers into them.