user: ### NOW ANSWER:
Question: How many silver medals did the country that won 20 gold medals win in the 1955 Pan American Games?
Columns: ['Rank', 'Nation', 'Gold', 'Silver', 'Bronze', 'Total']
Types: ['real', 'text', 'real', 'real', 'real', 'real']
Sample row: [1.0, 'United States', 20.0, 14.0, 8.0, 42.0]
SQL:

assistant: SELECT SUM("Silver") FROM "Table" WHERE "Gold" = 20.0;