Jane has a pre-paid cell phone with A Fee and Fee. She can't remember the exact costs, but her plan has a monthly fee and a charge for each minute of calling time. In June she used 220 minutes and the cost was $124.00. In July she used 710 minutes and the cost was $344.50.Express the monthly cost C as a function of x , the number of minutes of calling time she used. If Jane used 764 minutes of calling time in August, how much was her bill?