Ok so if each member of the jazz band sold the same amount of tickets, r, then we can write a linear equation (no exponents or anything). let y be the total number of raffle tickets sold. If they all sold the same amount, then we can simply multiply the number of people by the tickets they individually sold.
Since a square has all equal sides, this would mean the the all the other sides are 20 as well. To get the area, you would just multiply 20 by 20 to get 400. :)
