SELECT T2.name ,  avg(T1.age) FROM Person AS T1 JOIN PersonFriend AS T2 ON T1.name  =  T2.friend GROUP BY T2.name ORDER BY avg(T1.age) DESC LIMIT 1
Which person whose friends have the oldest average age?
[Schema (values) (types)]: | network_2 |  Person : name (text) , age (text) , city (number) , gender (text) , job (text) | PersonFriend : name (text) , friend (text) , year (number);