Context: CREATE TABLE journal_committee (journal_ID VARCHAR, work_type VARCHAR); CREATE TABLE journal (sales INTEGER, journal_ID VARCHAR)
Question: What is the average sales of the journals that have an editor whose work type is 'Photo'?
Answer: SELECT AVG(T1.sales) FROM journal AS T1 JOIN journal_committee AS T2 ON T1.journal_ID = T2.journal_ID WHERE T2.work_type = 'Photo'