What is the average of absence for an employed students?
average refers to DIVIDE(SUM(month), COUNT(name))
SELECT AVG(month) FROM longest_absense_from_school WHERE name NOT IN ( SELECT name FROM unemployed )
database name:db_id student_loan
bool table bool Cols: name dtype text, 
person table person Cols: name dtype text, 
disabled table disabled Cols: name dtype text, 
enlist table enlist Cols: name dtype text, organization dtype text, 
filed_for_bankruptcy table filed_for_bankruptcy Cols: name dtype text, 
longest_absense_from_school table longest_absense_from_school Cols: name dtype text, month dtype integer, 
male table male Cols: name dtype text, 
no_payment_due table no_payment_due Cols: name dtype text, bool dtype text, 
unemployed table unemployed Cols: name dtype text, 
enrolled table enrolled Cols: name dtype text, school dtype text, month dtype integer, 
