Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_19 (quantity_preserved VARCHAR, serial_numbers VARCHAR)
### Question:
What is the quantity preserved for the serial number of mallet and simple articulated locomotives?
### Answer:
SELECT quantity_preserved FROM table_name_19 WHERE serial_numbers = "mallet and simple articulated locomotives"