Sandra$$s Cutting Station is a new concept in haircuts; low cost and very quick. Set in a local mall, Jenny$$s offers $15$ minute haircuts for harried shoppers who do not have time for lengthy appointments. To ensure that the clients are in and out quickly, she schedules her $5$ employees based on expected client traffic. Each of the employees is paid $$1280$per month, with part of their pay coming from client tips. Jenny pays rent and overhead costs of $$2500$per month. Because of the quick nature of the service, Sandra doesn$$t have time to clean combs in between clients, so she uses a new comb for each customer, at a cost of $$0\mathrm{.}75$each. She also provides shampoo and conditioner for each client at a cost of $$0\mathrm{.}90$per client. The average price for a haircut is $$10$ Sandra pays herself $$5,500$ per month. What is Sandra contribution margin ratio?