In a 36.0 g sample of an iron oxide (Fe₂O₃) compound containing 28 g of Fe, what is the % by mass of each element (Fe and O) in this compound?
a) Fe: 77.8%, O: 22.2%
b) Fe: 28.0%, O: 72.0%
c) Fe: 50.0%, O: 50.0%
d) Fe: 80.0%, O: 20.0%