At a gas station the price of gas is $2.40 a gallon. draw a graph to represent the relationship between the cost of gas and the volume purchase. also write an equation using y= mx + b form.

Part A) The graph in the attached figure

Part B)

Step-by-step explanation:

Let

y------> the price of gas

x-----> the volume of gas purchase

we know that

The relationship between the cost of gas and the volume purchase represent a direct variation and remember that a relationship between two variables, x, and y, represent a proportional variation if it can be expressed in the form  

In a proportional relationship the constant of proportionality k is equal to the slope m of the line and the line passes through the origin

In this problem the constant of proportionality k is equal to

and the y-intercept b is equal to zero because the line passes through the origin

therefore

the linear equation is

using a graphing tool

see the attached figure

  the correct choice is marked

step-by-step explanation:

the first two graphs show multiple turning points. the last graphs matches the description in every detail.