What are the ages of the oldest and youngest user that were surveyed? Indicate their user id.
Oldest user refer to MAX(AnswerText) where questionid = 1; Youngest user refer to MIN(AnswerText) where questionid = 1

SELECT MAX(T1.AnswerText), MIN(T1.AnswerText) , ( SELECT T1.UserID FROM Answer AS T1 INNER JOIN Question AS T2 ON T1.QuestionID = T2.questionid WHERE T2.questionid = 1 ORDER BY T1.AnswerText LIMIT 1 ) AS "youngest id" FROM Answer AS T1 INNER JOIN Question AS T2 ON T1.QuestionID = T2.questionid WHERE T2.questionid = 1