Mario runs an entertainment venue. He had revenue last year of $500,000 by charging a $25 admission price to each customer. He incurred variable costs of $100,000 and fixed costs of $250,000. He is considering hiring a new full-time employee, and if he does, he will pay the new employee a $50,000 salar y. If he hires this new employee, how many additional customers will be needed to maintain his current operating income? (Enter a number only, rounded to the nearest whole number if necessary)