For this case, the first thing we must do is define a variable:
g: number of gallons of gas.
c (g): total cost.
We then have a linear function of the form:
c (g) = 2.19 * g
Answer:
A function notation to describe the relationship between the total cost c (g) and the number of gallons purchased is:
c (g) = 2.19 * g
