Question 1138576
C=1800+15x is the fixed and variable cost, where x is the number of people
30x is the revenue
30x=1800+15x is breakeven equation
15x=1800
x=120.  One won't break even with fewer than 120 people
Remember, as one sells a ticket, the gain is only $15, since another $15 is food/drink.

It is true that with 110 tickets, one will have $3300, but the costs are $1800 + (110*$15), because there are 110 people with food and drink expenses, so that is added to the cost and it is $1650 for a total cost of $3450.  The revenue is 110*$30 or $3300.