Thanks, I had edited my comment just a moment ago.
As far as RFK Jr., I think he should just said 'it's one-sixth the original price.' That's perfectly clear, even to MAGA.
The first part, $100 to $600, is (whoops) almost correct at 600% (actually it's 500%), but it's 83.3% decrease (600-100)/600)x100% in price. A 100% decrease would mean it's free.