Mei is looking for a job cutting hair. One option is self-employment at The Richmond Salon, where she would pay $639 per month to rent a station and keep all of her earnings. Another option is to work at a franchise, where she would just have to pay the salon $9 for every haircut. If she performed a certain number of haircuts every month, the amount paid to either salon would be the same. How many haircuts would that be? How much would Mei pay?