mary is looking for a job cutting hair. one option is self-employment at the manchester salon, where she would pay $840 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 $8 for every haircut. if she performed a certain number of haircuts every month, the amount paid to either salon would be the same. how much would mary pay? how many haircuts would that be?