SELECT st.department, ROUND(SUM(normal_salary - dock_salary)/COUNT(st.staff_id),2) average_actual_salary, ROUND(IFNULL(AVG(IF(st.staff_gender = 'male', normal_salary - dock_salary, NULL)),0),2) average_actual_salary_male, ROUND(IFNULL(AVG(IF(st.staff_gender = 'female', normal_salary - dock_salary, N...