Table: npr_locomotives
Columns: class
wheel_arrangement
fleet_number_s
manufacturer
year_made
quantity_made
quantity_preserved
year_s_retired

Question: What is the year retired of the locomotive which had the quantity made of 25?
SQL: SELECT "year_s_retired" FROM npr_locomotives WHERE "quantity_made" = '25'

Question: Which class had a quantity made of 20?
SQL: SELECT "class" FROM npr_locomotives WHERE "quantity_made" = '20'

Question: What is the locomotive class that has a wheel arrangement of 2-8-2 and a quantity made of 25?
SQL: SELECT "class" FROM npr_locomotives WHERE "wheel_arrangement" = '2-8-2' AND "quantity_made" = '25'

Question: What is the quantity preserved to the locomotive with a quantity made of 6?
SQL: SELECT "quantity_preserved" FROM npr_locomotives WHERE "quantity_made" = '6'