Question 1039198
this would be a partial function or what might be called a split function.


t = 300 for x <= 100


t = 300 + 1 * (x-100) for x > 100.


as long as the number of messages is less than or equal to 100, the first formula of t = 300 is used.


if the number of messages exceeds 100, then the second formula of t = 300 + 1 * (x - 100) is used.


assume the customer used 150 messages.
since the number of messages is greater than 100, the second formula kicks in.
the monthly charge is 300 + 1 * (150 - 100) = 300 + 1 * 50 = 300 + 50 = 350.


assume the customer used 90 messages.
since the number of messages is less than or equal to 100, the first formula kicks in.
the monthly charge is 300.