Can somebody explain this please?

My vector sold for $ 6,00
author fee: 3,30
Withholding Tax 30%: 1,68
my earning: 1,02
I don’t really understand this mathematics, 30% of what is 1,68.
I mean, 1 dollar of 6 is really BS, and Envato takes 4,30 (1 dollar buyer fee and 3,30 author fee).
Is this really fair?

Really, nobody?