person A 100k = 20% tax
person B 200k = 30% tax
person C 300k = 40% tax.
person A would pay 20% over 100k
person B would pay 30% over 200K and not 20% over 100k and then 30% over the other 100k
person C would pay 40% over 300k. and not 20% over the first 100k then 30% over another 100% and then 40% over another 100k