user: Question: What is the total number of viewers where the share is 7 and the week rank is 64?
Columns: ['#', 'Air Date', 'Timeslot', 'Rating', 'Share', '18-49', 'Viewers', 'Weekly Rank']
Types: ['real', 'text', 'text', 'text', 'real', 'text', 'text', 'text']
Sample row: [1.0, 'February 22, 2008', '9:00 P.M.', '4.6', 8.0, '2.4/7', '7.44', 'TBA']
SQL:

assistant: SELECT SUM("Viewers") FROM "Table" WHERE "Share" = 7.0 AND "Weekly Rank" = '64';