CREATE TABLE table_203_515 (id DECIMAL, "rank" DECIMAL, "city" TEXT, "passengers" DECIMAL, "ranking" DECIMAL, "airline" TEXT)

the difference in passengers between los angeles and toronto
SELECT (SELECT "passengers" FROM table_203_515 WHERE "city" = 'los angeles') - (SELECT "passengers" FROM table_203_515 WHERE "city" = 'toronto')
SELECT (SELECT "passengers" FROM "table_203_515" WHERE "city" = 'los angeles') - (SELECT "passengers" FROM "table_203_515" WHERE "city" = 'toronto')