What is the total expense for the Yearly Kickoff?
'Baseball game' is an event name; total expense refers to SUM(cost)
SELECT SUM(T3.cost) FROM event AS T1 INNER JOIN budget AS T2 ON T1.event_id = T2.link_to_event INNER JOIN expense AS T3 ON T2.budget_id = T3.link_to_budget WHERE T1.event_name = 'Yearly Kickoff'