user: Question: What is the average Frequency MHz that is on Farwell, Texas?
Columns: ['Call sign', 'Frequency MHz', 'City of license', 'ERP W', 'Class', 'FCC info']
Types: ['text', 'real', 'text', 'text', 'text', 'text']
Sample row: ['KASV', 88.7, 'Borger, Texas', '10,000 horizontal 3,000 vertical', 'C3', 'FCC']
SQL:

assistant: SELECT AVG("Frequency MHz") FROM "Table" WHERE "City of license" = 'Farwell, Texas';