Last year 190 student attended the spring dance and the total cost was 1250. two years ago 175 people attended and the total cost was 1175. determined the fixed cost, cost of a ticket. if 225 people attend this years dance, what would be the total cost?

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.