Reaction stoichiomerty help?i dont get the iron ore stuff at all and these things are due today!!:O

An ore contains Fe3O4 and no other iron. The
iron in a 40.2-gram sample of the ore is all
converted by a series of chemical reactions to
Fe2O3. The mass of Fe2O3 is measured to be
28.3 g. What was the mass of Fe3O4 in the
sample of ore?
Answer in units of g

A 19.2 g sample of iron ore is treated as
follows. The iron in the sample is all converted
by a series of chemical reactions to Fe2O3.
The mass of Fe2O3 is measured to be 20.4 g.
What was the mass of iron in the sample of
ore?
Answer in units of g

2 Fe3O4 + ... → 3 Fe2O3 + ...
(28.3 g Fe2O3) / (159.6887 g Fe2O3/mol) x (2/3) x (231.5333 g Fe3O4/mol) =
27.4 g Fe3O4

2 Fe + ... → Fe2O3 + ...
(20.4 g Fe2O3) / (159.6887 g Fe2O3/mol) x (2/1) x (55.8452 g Fe/mol) = 14.3 g Fe