van der Waals equation

It turns out that the van der Waals constant b equals four times the total volume actually occupied by the molecules of a mole of gas. Using this figure, calculate the fraction of volume in a container actually ocupied by Ar atoms (a) at STP, (b) at 100 atm pressure and 0 degrees celsius. (Assume for simplicity that the ideal-gas equation still holds.)

Why did you choose that subject?

because it's a van der Waals question

the only thing i know is van der waals forces is why water is liquid not gas.

no matter how many times I read that question, I just don't get it. Hahahah

still don't know what I'm doing.
any takers? Hahah