Question

I dont know how to do this so whatever helps:)

Answer 1

The function which represents the phone rate is a straight line, which can be gotten by the following formula:

`y=mt+b`

Where m is the slope, and b the point where the y-axis is crossed by the line.

Let's get the slope first:

`m=(27-25)/(20-0)=(2)/(20)=(1)/(10)`

And b = 25 because (0, 25) is where the line has crossed the cost axis.

Therefore:

`y=C(t)=(1)/(10)t+25`