Answer:
the 3rd one
Step-by-step explanation:
A proportional relationship has to have a Stright line. Hope this helps :)
B
If we make a graph comparing the total cost of the milk and the gallons bought, it will be a straight line, which is a constant rate of change.
2.70$
2, I think. Lines 1 & 2 and lines 7 & 4 are perpendicular
edit: 3 pairs, 3 & 5 is the last one
