Answer:
Correct option: first one
Step-by-step explanation:
The graph has 3 different parts:
Cost = 15 when the Gigabytes used is lesser than or equal 2,
Cost from 20 to 40 when the Gigabytes used is greater than 2 and lesser than or equal 6.
An increase of 4 gigabytes caused an increase of 20 in the cost, so the slope is 20/4 = 5, and the y-intercept is:
20 = 5*2 + b -> b = 10
Cost = 50 when the Gigabytes used is greater than 6.
So the correct option is the first one
