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_73 (tonnage INTEGER, type_of_ship VARCHAR, date_entered_service VARCHAR)
### Question:
what is the sum of tonnage when the type of ship is twin screw ro-ro motorship and the date entered service is 11 february 1983?
### Answer:
SELECT SUM(tonnage) FROM table_name_73 WHERE type_of_ship = "twin screw ro-ro motorship" AND date_entered_service = "11 february 1983"