Answer:
Well, I don't know how to graph it for you, but the slope is -2/3 and the point is (-9, 5). So, when you graph it, from the point (-9, 5), you can go 3 units to the right and 2 units down.
Since we are finding the unit rate of the cost per comic, we will need to divide $5 by 20 comics which you will get 0.25 cents and divide $7.50 by 30 comics which you will also get 0.25 cents.Therefore, the unit rate and constant of proportionality is 0.25 cents.