If your buddy on E85 is running a map cut back 35% and you are running a map cut back 55%, he is running approximately 44% more fuel than you if you both are cutting back from the same starting point.
He’s running 100%-35% = 65% of starting point amount of fuel
You’re running 100%-55% = 45% of starting point amount of fuel
65-45 = 20 difference in values
20/45 = .44 = 44% difference in final values = 44% more fuel.