Hello!  How are you?  Can you please provide me with a list of all department IDs, department names, and their respective years of creation?
select department_id, name, creation from department
Excellent!  Can you filter this list to include only the rows that contain the most common (most frequently occurring) year of creation?
select department_id, name, creation from department where creation = ( select creation from department group by creation order by count ( * ) desc limit 1 )
Perfect! Can you tell me what is the total combined budget of these two departments?
select sum ( budget_in_billions ) from department where creation = ( select creation from department group by creation order by count ( * ) desc limit 1 )