The equation will be the same as it is already balanced.
To find out whether the equation is balanced or not you can put the numbers of elements in front of you.
To show:-
BaO + SO2 —->> BaSO3
The reactants:-
Ba=1
O=2+1 (Be sure to seperate them in order to get proper results as they are there in seperate amounts)
S=1
The products:-
Ba=1
O=3
S=1
