The phone company splint has a monthly cellular plan where a customer pays a flat monthly fee and then a certain amount of money per minute used on the phone. if a customer uses 470 minutes, the monthly cost will be $162. if the customer uses 540 minutes, the monthly cost will be $183. a. find an equation in the form y = m x + b , y=mx+b, where x x is the number of monthly minutes used and y y is the total monthly of the splint plan.