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_88 (silver INTEGER, bronze VARCHAR, total VARCHAR)
### Question:
For all countries with 7 bronze medals and a total number of medals less than 13, what's the sum of silver medals?
### Answer:
SELECT SUM(silver) FROM table_name_88 WHERE bronze = 7 AND total < 13