Question

A compound that contains only Fe and O is 69.9% Fe by mass. What is the empirical formula of theis compound?

Attempt: 69.9g(1/56): 1
30.1g(1/16): 2

I got FeO2

but the answers say that it is Fe2O3
Amy~
I got it since O comes out to be 1.5 * 2 = 3