CREATE TABLE table_56210 ("Class" TEXT, "Wheel arrangement" TEXT, "Manufacturer" TEXT, "Year made" TEXT, "Quantity made" TEXT, "Quantity preserved" TEXT, "Year ( s )  withdrawn" TEXT)

What was the quantity preserved for quantity made of 15?
SELECT "Quantity preserved" FROM table_56210 WHERE "Quantity made" = '15'
SELECT "Quantity preserved" FROM "table_56210" WHERE "Quantity made" = '15'