A telecommunications company provides landline services. The company stipulates that the tariff paid in a regional unit for a month is calculated by multiplying the call duration (in minutes) by the call rate per minute, then adding the monthly subscription fee.
The rate per minute set in region A is Rp more than the call duration (in minutes). The tariff paid by a customer for a month is denoted by , the call duration (in minutes) is denoted by , and the monthly subscription fee is denoted by . The monthly subscription fee is set at Rp.
Which of the following is the function for the landline tariff paid by a customer for a month?