user: Question: What was the sum of Value ($M), when the Revenue ($M) was less than 307, the Team was valencia, and the Rank was smaller than 19?
Columns: ['Rank', 'Team', 'Country', 'Value ($M)', 'Debt as %of value', '% change on year', 'Revenue ($M)', 'Operating income($m)']
Types: ['real', 'text', 'text', 'real', 'real', 'text', 'real', 'real']
Sample row: [1.0, 'Manchester United', 'England', 1800.0, 60.0, '24', 394.0, 111.0]
SQL:

assistant: SELECT SUM("Value ($M)") FROM "Table" WHERE "Revenue ($M)" < 307.0 AND "Team" = 'valencia' AND "Rank" < 19.0;