You are at The Mall of America searching for a new cell phone. You have identified two plans that work for you. The first plan is through Fast Communications. The second plan is through P-Wireless. Fast Communications charges a monthly fee of $15.20 for text messaging, call waiting, and caller ID. Fast Communications also charges you 70 cents per minute to use the phone. P-Wireless charges a monthly fee of $9.50 for text messaging, call waiting, and caller ID. P-Wireless charges you 90 cents per minute to use the phone. Model the scenario with a system of linear equations, where x represents the number of additional minutes used and y represents the total monthly cost.