Answer:
2 Fe + 3 Br₂ → 2 FeBr₃
Step-by-step explanation:
There are 2 Br atoms on the left, and 3 on the right. So put a 3 in front of Br₂, and a 2 in front of FeBr₃.
_Fe + 3 Br₂ → 2 FeBr₃
Now there's 6 Br atoms on each side. There are 2 Fe atoms on the right side, so put a 2 in front of Fe:
2 Fe + 3 Br₂ → 2 FeBr₃
Now the equation is balanced.