Empirical Formula of an Oxide?

The m of phosphorous is 0.407 the m of oxygen will be the m of oxide less that of phosphorous(p)= 0.58 molar m of P. Is 31 and that of oxygen is 16. We determine the number of moles of each (which=m/molar m). That of P will be 0.407 and that of oygen 0.58 you divide this by the least value and get a whole number ratio.you'll get 1 : 3 so the empirical formula will be PO3