CREATE TABLE table_13999 ("City" TEXT, "System" TEXT, "Category" TEXT, "Daily ridership" FLOAT, "As of" TEXT, "Opened" FLOAT, "Stations" TEXT)

Which Opened has a System of c-train, and a Daily ridership smaller than 269,600?
SELECT MAX("Opened") FROM table_13999 WHERE "System" = 'c-train' AND "Daily ridership" < '269,600'
SELECT MAX("Opened") FROM "table_13999" WHERE "Daily ridership" < '269,600' AND "System" = 'c-train'