For this case we have that by definition, a direct variation is given by:
Where:
k: It is the constant of proportionality of the variables.
On the other hand, we have that the inverse variation is given by:
Where:
k: It is the constant of proportionality of the variables.
In this way, the correct option is: 
ANswer:
Option A
Yes it is linear
It is a negative slope
I am attaching pic of graph
The slope is -3/4
Y intercept is (0,2)
I agree with Roaltyjess<span />
To find how many minutes of talk time is available per dolla, you have to divide 160 (number of minutes) by 40 (cost)
160/40 = 4
Therefore, it's 4 minutes per dollar
The top right one is not a function
