To find the change in Devon's account each month after paying for the internet service, we need to determine how much he paid each month.
Devon made payments totaling $936 over 8 months. To find the monthly payment, we divide the total by the number of months:
\[ \text{Monthly Payment} = \frac{936}{8} = 117 \]
Since this is an expense, the change in Devon's account each month after paying for the service is negative. Therefore, the change in Devon's account each month is:
\[ -$117 \]
The correct response is:
-$117