Why So much reduction in income!!

Hello every body
I wanna know why Envato reduces this much from our income!
What is US back up witholding Tax?
And what is author fee for sale?!
I work on VH.My item is 14$,and i am exclusive…Every sale gives me just 4$!!!
Why so much reduction?!

Thanks in advance!

It seems you are living in a country which has a 30% tax treaty with USA

Have you completed your tax information under your profile settings?