Add S/3 to each side: 0>6+S/3. Multiply through by 3: 0>18+S or 18+S<0; subtract 18 from each side: S<-18. This answer is not shown. C and D answer options are the same. I think one of them should be S<-18, probably D.
Another way: -S/3>6. Transfer minus to the other side and reverse the inequality: S/3<-6. Multiply through by 3: S<-18.
There are many ways to get the answer, but it will always be the same.