user: ### NOW ANSWER:
Question: Which Bronze has a Silver of 15, and a Gold smaller than 20?
Columns: ['Rank', 'Nation', 'Gold', 'Silver', 'Bronze', 'Total']
Types: ['real', 'text', 'real', 'real', 'real', 'real']
Sample row: [1.0, 'Italy', 29.0, 28.0, 23.0, 80.0]
SQL:

assistant: SELECT SUM("Bronze") FROM "Table" WHERE "Silver" = 15.0 AND "Gold" < 20.0;