Final answer:
Subtracting the yearly fee from John's total computer help budget and dividing the remaining amount by the cost per help session determines that John can afford a maximum of 13 help sessions.
Step-by-step explanation:
John has a maximum budget of $170 for a computer help service with a yearly fee of $25.50 and a charge of $10.50 per help session. First, we must subtract the yearly fee from the total budget to see how much is left for the help sessions:
$170 - $25.50 = $144.50
Now, we will divide the remaining amount by the cost of each help session to determine the maximum number of sessions John can use:
$144.50 / $10.50 ≈ 13.76
Since John cannot attend a fraction of a session, he can attend a maximum of 13 help sessions this year within his budget.