user: Question: Which Frequency MHz has a ERP W of 250?
Columns: ['Call sign', 'Frequency MHz', 'City of license', 'ERP W', 'Class', 'FCC info']
Types: ['text', 'real', 'text', 'real', 'text', 'text']
Sample row: ['K210CB', 89.9, 'Broken Bow, Nebraska', 250.0, 'D', 'FCC']
SQL:

assistant: SELECT "Frequency MHz" FROM "Table" WHERE "ERP W" = 250.0;