Question

Skylar has a smart phone data plan that costs $50 per month that includes 7 GB of data, but will charge an extra $30 per GB over the included amount. How much would Skylar have to pay in a month where she used 5 GB over the limit? How much would Skylar have to pay in a month where she used went over by xx GB?

Answer 1

If Skylar went 5 GB over the limit she will have to pay $200 for that month;

If she went "x" GB over the limit, she will have to pay 50 + 30*x.

Explanation:

Skylar's plan has a fixed fee of $50 for any value of data usage that is below 7 GB, but charges an extra of $30 per GB over that. For cases where she went over the limit by "x" GB, the cost of her plan is given by:

`cost(x) = 50 + 30*x`

If she went 5 GB over the limit, she'll have to pay:

`cost(5) = 50 + 30*5\\cost(5) = 50 + 150\\cost(5) = 200`

She will have to pay $200.