Using a linear function, it is found that Sarah can use 3.7 gigabytes while staying within her budget.
What is a linear function?
A linear function is modeled by:
y = mx + b
In which:
- m is the slope, which is the rate of change, that is, by how much y changes when x changes by 1.
- b is the y-intercept, which is the value of y when x = 0, and can also be interpreted as the initial value of the function.
Considering the flat cost as the y-intercept and the cost per gigabyte as the slope, the cost of using g gigabytes is:
C(g) = 4g + 69.
She wants to keep her bill at $83.80 per month, hence:
C(g) = 83.80
4g + 69 = 83.80
4g = 14.80
g = 14.80/4
g = 3.7.
Sarah can use 3.7 gigabytes while staying within her budget.
More can be learned about linear functions at https://brainly.com/question/24808124
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