a. Let y = the monthly cost
Let x = the number of GB of data used per month
Equation
Then, the equation that model the cell phone plan is:

Table
x = -5

x = -3

x = 0

x = 1

x = 2

Therefore, the table is:
x y
-5 -5
-3 15
0 45
1 55
2 65
Graph
We graph the equation y = 10x + 45
b. Unlimited data costs $100, this is y = 100, therefore:

And solve for x

Answer: 5.5 GB