3 f. Fe⁺³ and O<sup>-2

Need to make the compound neutral by balancing positive and negative ions:
Need two iron and three oxygen

Fe</sup>₂O₃

two non metals? no
metal/nonmetal? yes
metal with more than one charge?yes

Fe has a charge of +3 and compound is binary so -ide on end of nonmetal

iron (III) oxide