user: Question: What is the average Frequency, when Type is "Norteño", and when Brand is "La Cotorra"?
Columns: ['Frequency', 'Callsign', 'Brand', 'City of License', 'Type']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [580.0, 'XEHP', 'La Mas Prendida', 'Ciudad Victoria', 'Norteño']
SQL:

assistant: SELECT AVG("Frequency") FROM "Table" WHERE "Type" = 'Norteño' AND "Brand" = 'La Cotorra';