Ryan J. answered 6d
Tutor
New to Wyzant
25 years experience
Get an even number of oxygen on the left, because the right side can never be odd, by putting a 2 in front of SO3
_2_SO3 --> ___SO2 + ___O2
Balance the Sulfur by putting a 2 in front of SO2 and you are done
_2_SO3 --> _2_SO2 + ___O2