Math in it's most basic form:
Say 1000 went last year to HHN 25
800 bought 1 day tickets for $101.99 (equaling $81,592) and 200 people bought FFP basic at $110.99 (equaling $22.198), the event would have brought in a revenue from tickets of $103,790
Let's say this year in 2016, Universal increases 1 day tickets to the normal goings and it goes to $105.99. Now let's say Universal does dramatically hike up FFP basic to $179.99. Fans are upset so only 100 people end up buying the FFP for a revenue of $17,999.00. The other 100 opt for 1-day tickets, so 900 tickets sold equals to $95,391.00.
Total 2016 revenue from those 1000 = $113,390.00
Again, this is incredibly simplifying things to the most basic kind of figures. Obviously not accounting drinks, food, staying on-site, merch etc..... but the point is there.