Jane has a prepaid cell phone with Ringular. 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 390 minutes and the cost was $90.50. In July, she used 950 minutes and the cost was $174.50.
A) Express the monthly cost CC in terms of xx, the number of minutes of calling time she used.
Answer:
B) If Jane used 638 minutes of calling time in August, how much was her bill?
Answer: $