Stochiomety Help (Chemistry)

I'm having trouble with Stoichiometry. Can someone help me with a problem like the following, I've already balanced the original equation for you.

"Given the reaction 4(NH3) + 5(O2) --> 4(NO) + 6(H2O) how many grams of ammonia (NH3) are required to react with 80g of Oxygen?"

I know this involves converting to moles somewhere but I'm havng a little trouble remebering, please help!

First off, convert grams to moles. 80/32 (O2 is 32 grams, not 16). Now, do a mole to mole ratio. Multiply moles of oxygen by moles of NH3 (4), and divide that by 5 (moles of O2). You now have the moles of NH3. Convert that to grams (mol NH3 x g NH3).

-IANVS

EDIT
Stoichiometry! It's an ATTITUDE!

Originally Posted by Janus

First off, convert grams to moles. 80/32 (O2 is 32 grams, not 16). Now, do a mole to mole ratio. Multiply moles of oxygen by moles of NH3 (4), and divide that by 5 (moles of O2). You now have the moles of NH3. Convert that to grams (mol NH3 x g NH3).

-IANVS

EDIT
Stoichiometry! It's an ATTITUDE!

Yeah I eventually figured that out. I ended up getting 68g of NH3, is that correct. If so then I think I got the hang of this.

I just did this:

(in "analysis" format - the format they use in U/C)

80g O2 x 1 mol O2/ 16g O2 x 4 mol NH3/ 5 mol O2 x 17g NH3 / 1 mol NH3 = 68 g NH3