user: Question: what is the class of the station with erp w more than 30?
Columns: ['Call sign', 'Frequency MHz', 'City of license', 'ERP W', 'Class', 'FCC info']
Types: ['text', 'real', 'text', 'real', 'text', 'text']
Sample row: ['W294AJ', 106.7, 'Charlottesville, Virginia', 21.0, 'D', 'FCC']
SQL:

assistant: SELECT "Class" FROM "Table" WHERE "ERP W" > 30.0;