CREATE TABLE table_name_87 (year NUMBER, cause VARCHAR2, death_toll VARCHAR2)

Which Year has a cause of firedamp and a Death toll larger than 11?
SELECT SUM(year) FROM table_name_87 WHERE cause = "firedamp" AND death_toll > 11
SELECT SUM("year") FROM "table_name_87" WHERE "cause" = "firedamp" AND "death_toll" > 11