The owner of a skate park wants to increase her entry fee of $5.00 by an increment of $0.50. Currently the skate park has an average of 500 paying customers per week. The expression (500-25x)(5.00+0.50x) gives the estimated weekly income, where x is the number of $0.50 entry fee price increases. If the entry fee is increased to $7.50, what will be the expected average number of paying customers each week?