Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_4856 ( "Rank" real, "Nation" text, "Gold" real, "Silver" real, "Bronze" real, "Total" real )

### Question ###
How many silver medals did the country that won 20 gold medals win in the 1955 Pan American Games?

### Accurate SQL ###

SELECT SUM("Silver") FROM table_4856 WHERE "Gold" = '20'