SELECT avg(age) FROM Student WHERE StuID IN ( SELECT T1.StuID FROM Has_allergy AS T1 JOIN Allergy_Type AS T2 ON T1.Allergy  =  T2.Allergy WHERE T2.allergytype  =  "food" INTERSECT SELECT T1.StuID FROM Has_allergy AS T1 JOIN Allergy_Type AS T2 ON T1.Allergy  =  T2.Allergy WHERE T2.allergytype  =  "animal")
Find the average age of the students who have allergies with food and animal types.
SELECT avg ( age ) FROM Student WHERE StuID IN ( SELECT T1.StuID FROM Has_allergy AS T1 JOIN Allergy_Type AS T2 ON T1.Allergy = T2.Allergy WHERE T2.allergytype = `` food '' INTERSECT SELECT T1.StuID FROM Has_allergy AS T1 JOIN Allergy_Type AS T2 ON T1.Allergy = T2.Allergy WHERE T2.allergytype = `` animal '' )
select avg ( age ) from student where stuid in ( select t1 . stuid from has_allergy as t1 join allergy_type as t2 on t1 . allergy = t2 . allergy where t2 . allergytype = value intersect select t1 . stuid from has_allergy as t1 join allergy_type as t2 on t1 . allergy = t2 . allergy where t2 . allergytype = value )
Find the average age of the students who have allergies with food and animal types .