Martha has asked you to evaluate her business, Martha's Tattoo Salon. Martha has five tattoo artists working for her. (Martha is not one of them.) Each tattoo artist is paid $9.90 per hour and works 40 hours a week and 50 weeks a year, regardless of the number of tattoos. Rent and other fixed expenses are $1,750 per month. Assume that the only service performed is the giving of tattoos, whose unit price is $12. Find the contribution margin per tattoo.