Defence and armor stats

Ok, so I can’t find the exact calculation procedure, but what I think is going on is: your armor/resistance base stats are increased by applying certain gear pieces and by increasing strength, agility and tactics, this base value is then represented as a percentage through some formula, your mods then increase your defense, which will be again turned into a percent and applied equally to both armor and resistance. The reason it doesn’t appear as though your armor and resistance stats are being increased equally though I think is due to the base stat not being the same and then the conversion to percent makes the the same numerical value appear as a different percentage.