Answer:
The slope is $0.35/min and it gives the cost per minute of the phone used.
Step-by-step explanation:
We can model this situation with a linear equation of the form
where is monthly cost,
is the number of minutes,
is the flat monthly fee, and
is the slope of the equation, or in our case, the amount of money charged per minute.
The slope is
,
in other words, the phone company charges $0.5 per minute.
With the slope in hand, the linear equation becomes
,
and we can find the monthly fee from that fact that for 300 minutes the cost is $131:
.
Therefore,
where the slope if the equation give the cost per minute of the phone used.