CREATE TABLE table_66809 ("Rank" TEXT, "Nation" TEXT, "Gold" FLOAT, "Silver" FLOAT, "Bronze" FLOAT, "Total" FLOAT)

For all countries with 7 bronze medals and a total number of medals less than 13, what's the sum of silver medals?
SELECT SUM("Silver") FROM table_66809 WHERE "Bronze" = '7' AND "Total" < '13'
SELECT SUM("Silver") FROM "table_66809" WHERE "Bronze" = '7' AND "Total" < '13'