Answer:
4 Fe + 3 O₂ → 2 Fe₂O₃
Step-by-step explanation:
Let's start with the oxygen.
Reactants - 2
Products - 3
What number do 2 and 3 have in common? 6.
Put a 3 in the reactants and a 2 in the products to balance the oxygen.
Fe + 3 O₂ → 2 Fe₂O₃
Now let's look at the iron.
Reactants - 1
Products - 4
Put a 4 in the reactants to balance the iron.
4 Fe + 3 O₂ → 2 Fe₂O₃
The equation is balanced. Hope that helps.