What is the average vacation hours taken by Sales person?
Store Contact refers PersonType = 'SC'; AVG(VacationHours
SELECT CAST(SUM(T1.VacationHours) AS REAL) / COUNT(T1.BusinessEntityID) FROM Employee AS T1 INNER JOIN Person AS T2 ON T1.BusinessEntityID = T2.BusinessEntityID WHERE T2.PersonType = 'SP'