Converting from Grams to Molecules I was doing some problems from the textbook on converting between units using dimensional analysis and I came across this problem.

A vat of Hydrogen Peroxide ($\ce{H2O2}$) contains
455 grams of oxygen atoms. How many
molecules of ($\ce{H2O2}$) are in the vat?

Sorry if I didn`t format the question correctly, I am a still a newbie.
But how would I set this up? I would not like the answer to this question but I would like some input on how would I get how many molecules of hydrogen peroxide from grams of oxygen atoms? Any help would be much appreciated. Thanks in advance!
A vat of Hydrogen Peroxide ($\ce{H2O2}$) contains 455 grams of oxygen atoms.
  How many molecules of ($\ce{H2O2}$) are in the vat?



How many moles of oxygen atoms are in 455 gms of oxygen atoms? Let's call the answer $x$.
How many moles of $\ce{O2}$ are in $x$?  Let's call the answer $y$.
How many moles of $\ce{H2O2}$ could you make from $y$ moles of $\ce{O2}$?  Let's call the answer $z$.
1 mole of any substance contains Avogadro's number of molecules.  How many molecules are in $z$ moles?