Using stoichiometric factor calculation, how is this solved?

The phosphorous in a 0.2374 gram sample was precipitated as the slightly soluble (NH4)3.12MoO3. This precipitate was filtered, washed, and then redissolved in acid. Treatment of the resulting solution with an excess of Pb2+ was resulted in the formation of 0.2752g of PbMoO4. Express the results of this ysis in terms of percent P2O5.