Acustomer calls and has questions about the bill for their first month's subscription. they want to know why the monthly rate is $45.00, but the bill is for $60.00. what is the most likely reason for the bill being this amount?

The most likely thing that has happened in this case is that a fee is paid for the registration.
 The function that best models this problem is:
 y = 45x + 15
 Where,
 x: number of months.
 Y: payment of each month.
 For the first month we have:
 y = 45 (1) +15
 y = 45 + 15
 y = 60
 
 the most likely reason for the bill being this amount is
 registration fee.