Help me understand Weights and Normalization please
Okay so I'm making a pbbg, and I've hit a bottleneck making the crafting system. I have it set up in tiers from T0-7 with T0 being a linear decline from 100% when player lvl is 0, to 0% when player level is 10, then T7 is also linear from 0% at lvl 0 to 0.001% at lvl 100, the following tiers T1-3 will be accessible for a time, then fade away so that players aren't using obsolete equipment forever, which then has me assume that T4-6 will be piecewise functions that will need to change their rate of growth since these never decline.
All that aside, I'm confused on how I'm supposed to get those values and then turn it into a percentage, because the route I keep in heading is
"well because T0 is at 60% at lvl 4 then T1 can't be more than 40%, but I still have to consider T2-6 because T7 is also increasing linerarly"
Which then spirals me into trying to find equations that fill the gap of percentages, but I've been told that normalization handles that at the end, and assigning weights is what "keeps the percentages consistent", but I'm having trouble understanding that concept.
If anyone has any resources to learn this area of math, that'd be much appreciated, I prefer to see how it's done visually so that I may understand the applications of the variables when I translate it all to code later.