$100 increasing to $600 is a 500% increase.
That’s all anyone needs to know about this interaction. Oh and that the 10 people who agreed with RFK here, or said nothing, are equally as stupid as he is.
RFK Jr: "A Democratic senator claimed it's mathematically impossible to have a drug drop by 600%. I said, 'Well, if the drug was $100 and it raises to $600, that would be a 600% rise. If it drops from $600 to $100, that's a 600% savings.'"
Trump: "Right"