The answer correct answer is 80.5
It's a linear function. We need only two points to draw a graph.
We choose any values of x and calculate the value of y.

for x= 0 → y = 3(0) - 1 = 0 - 1 = -1 → (0, -1)
for x = 2 → y = 3(2) - 1 = 6 - 1 = 5 → (2, 5)

for x = 0 → y = 3(0) - 1/3 = 0 - 1/3 = -1/3 → (0, -1/3)
for x = 2 → y = 3(2) - 1/3 = 6 - 1/3 = 5 2/3 → (2, 5 2/3)
Start at 5 and go up 3 and move 4 to the right
The answer is B because Chris and three of his friends is 4. Then, each person paid $9 so 4 x 3 = x.