CREATE TABLE "medal_table" (
  "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?
SQL: SELECT SUM("silver") FROM "medal_table" WHERE "gold"=20;