Y =

This is because the total cost is 10x + 480 and then that needs to be divided by the amount of people.
Answer:
B
Step-by-step explanation:
The best - well, only way- is to check a few points.
Namely -1 (unless your eyesight is really poor!), 0, 1, 2, and 3.

Now you can mark all these points in each graph (well, you could if they were on paper and not on a screen) and see which one of the lines passes through all of them. Spoiler alert, it's the B graph.
A represents
, B is the one you want, C is
and D looks like 
Algebra is really easy when you try your hardest. What seems to be troubling you friend?