Unit cost of a ticket = Income from ticket sales / number of tickets sold:
$1250 --------------- = $6.58 per ticket 190 tickets
Again:
$1175 --------------- = $6.71 175 tickets
While ticket prices do change (usually increase) from year to year, it's unusual to see such a situation here.
Don't have any guidelines by which to determine the "fixed cost of a ticket".
If we use the cost of a ticket of 2 years ago ($6.58/ticket), then the income from the sale of 225 tickets this year would be ($6.58/ticket)(225 tickets), or $1480.50.
