First we have to determine how many chairs there are total. To do this multiply 9 by 28
9*28 = 252
That means you have a total of 252 chairs. Since we can assume that every person who buys a $4 ticket will only sit in one chair, we can say that if all the seats are filled then 252 people bought a ticket
To find the total price multiply the total chairs by the cost per ticket (or chair, which ever way you want to think of it as)
252 * 4 = 1008
You would make $1008
Hope this helped!
~Just a girl in love with Shawn Mendes