Answer:
3K2BrSO4
Explanation:
There are a total of 2 aluminum atoms and B3 bromine atoms on the left side while on the right side there are 6 potassium atoms, 6 bromine atoms, 2 aluminum atoms, 3 sulfur atoms, and 12 oxygen atoms. So you need 6 potassium atoms, 3 bromine atoms, 3 sulfur atoms, and 12 Oxygen atoms on the left side.
