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_1776943_1 (broadcast_date VARCHAR, viewers__in_millions_ VARCHAR, archive VARCHAR)
### Question:
Name the broadcast date for 6.4 million viewers for the archive of 16mm t/r
### Answer:
SELECT broadcast_date FROM table_1776943_1 WHERE viewers__in_millions_ = "6.4" AND archive = "16mm t/r"