Database: human_resources
Question: Calculate the monthly average salary of the employee with highest salary. Mention his name, position title and location city.
SQL: SELECT SUM(CAST(REPLACE(SUBSTR(T1.salary, 4), ',', '') AS REAL)) / 12 AS avg, T1.firstname, T1.lastname , T2.positiontitle, T3.locationcity FROM employee AS T1  INNER JOIN position AS T2  ON T1.positionID = T2.positionID INNER JOIN location AS T3  ON T1.locationID = T3.locationID WHERE CAST(REPLACE(SUBSTR(T1.salary, 4), ',', '') AS REAL) = ( SELECT MAX(CAST(REPLACE(SUBSTR(T1.salary, 4), ',', '') AS REAL)) FROM employee AS T1  INNER JOIN position AS T2  ON T1.positionID = T2.positionID INNER JOIN location AS T3  ON T1.locationID = T3.locationID )