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_6 (year_of_marriage INTEGER, her_age VARCHAR, his_age VARCHAR)
### Question:
What is the mean year of marriage when her age was more than 19 and his age was 30?
### Answer:
SELECT AVG(year_of_marriage) FROM table_name_6 WHERE her_age > 19 AND his_age = 30