Question

For his mobile phone service, John pays a monthly fee of $40 plus $15 for each 1 GB of data (rounded up) over his 8 GB of data that comes with his plan. For his monthly charge before taxes to be at most $70, how many gigabytes of data can he use in a month

Answer 1

John can use no more than 2 GB of additional data

Explanation:

Monthly fee = $40

Additional fee = $15 for each 1 GB of data (rounded up) over his 8 GB.

Let x be the number of additional data in GB over his 8 GB of data that comes with his plan.

Total monthly charge is

`C(x)=40+15x`

It is given that monthly charge before taxes to be at most $70.

`C(x)\leq 70`

`40+15x\leq 70`

`15x\leq 70-40`

`15x\leq 30`

Divide both sides by 2.

`x\leq 2`

Therefore, John can use no more than 2 GB of additional data.