CREATE TABLE table_64260 ("Class" TEXT, "Railway number ( s ) " TEXT, "Quantity" TEXT, "Year ( s )  of manufacture" TEXT, "Type" TEXT)

What is the quantity of the aw class?
SELECT "Quantity" FROM table_64260 WHERE "Class" = 'aw'
SELECT "Quantity" FROM "table_64260" WHERE "Class" = 'aw'