[Deafboy]

An ore containing magnetite, Fe₃O₄, was analyzed by dissolving a 1.5149 g sample in conentrated HCL, yielding a mixture of Fe²⁺ and Fe³⁺, the resulting solution was diluted with water (to 50.00 ml) and the Fe³⁺ precipitated as Fe(OH)₃ by adding NH₃. After filtering and rising, the residue was ignited, yielding 0.8525g of pure Fe₂O₃.

What is  the weight percent Fe₃O₄ in the sample? What is the % w/w Fe?

I know this is probably easy but im lost 

[Borek]

Please read forum rules.

Start with reaction equations.