Since it is perpendicular to y=3x-1, the slope must be a negative reciprocal.
there the slope of the perpendicular line is

So now we have,

To find b, we use the point that the line passes through and substitute it to the y and x values.

which would give us b=5/3
Therefore, the equation of the line is
A=$20.20/10gal=$2.02 per gal
B=$26.04/12gal=$2.17 per gal
C=$28.14/14gal=$2.01 per gal
D=$30.45/15gal=$2.03 per gal
So C is the cheapest per gallon.
Answer:
use the verticle line test. if a verticle line touches two points on the graph then it is not a function, if the verticle line only touches one point then it is a function.
for your question the answer is the 3rd option - Graph with 5 points plotted at (negative 3, 2), (negative 2, negative 1), (0, 3), (1, 0), and (2, negative 3)