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_75 (year_opened INTEGER, material VARCHAR, span_feet VARCHAR)
### Question:
What is the sum of Year opened when steel was the material with a Span feet of 1476?
### Answer:
SELECT SUM(year_opened) FROM table_name_75 WHERE material = "steel" AND span_feet = 1476