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_20 (quantity VARCHAR, year_s__of_manufacture VARCHAR, class VARCHAR)
### Question:
what is the quantity when the year of manufacture is 1900 and the class is mc?
### Answer:
SELECT quantity FROM table_name_20 WHERE year_s__of_manufacture = "1900" AND class = "mc"