Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.

### Instruction:

Convert text to sql: Which person whose friends have the oldest average age? | person : name , age , city , gender , job | personfriend : name , friend , year | personfriend.friend = person.name | personfriend.name = person.name | 

### Response:

select _ , avg ( _ ) from _ group by _ order by avg ( _ ) desc limit _ | select personfriend.name , avg ( person.age ) from person join personfriend on person.name = personfriend.friend group by personfriend.name order by avg ( person.age ) desc limit 1