Table schema:
CREATE TABLE table_name_24 (time VARCHAR, news_freq VARCHAR, local_networked VARCHAR, ad_freq VARCHAR)

Question: Which time has a local/networked value of Local, ad frequency of every 20 minutes, and news frequency of n/a after 7PM news?
SQL: SELECT time FROM table_name_24 WHERE local_networked = "local" AND ad_freq = "20 minutes" AND news_freq = "n/a after 7pm news"