user: Question: Name the sum of frequecy with brand of Exa FM
Columns: ['Frequency', 'Callsign', 'Brand', 'Format', 'City of License', 'Website', 'Webcast']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [88.1, 'KHOY', 'Catholic Radio', 'Religious', 'Laredo', 'khoy.org', 'listen live']
SQL:

assistant: SELECT SUM("Frequency") FROM "Table" WHERE "Brand" = 'Exa FM';