CREATE TABLE table_8808 ("Class" CLOB, "Wheel arrangement" CLOB, "Fleet number ( s ) " CLOB, "Manufacturer" CLOB, "Year made" CLOB, "Quantity made" CLOB, "Quantity preserved" CLOB)

How many did alco -schenectady preserve of class b-3?
SELECT "Quantity preserved" FROM table_8808 WHERE "Manufacturer" = 'alco -schenectady' AND "Class" = 'b-3'
SELECT "Quantity preserved" FROM "table_8808" WHERE "Class" = 'b-3' AND "Manufacturer" = 'alco -schenectady'