First, we have to find out how much the monthly fee is.
So to do that we take .30 and multiply that by 120 and you get 36.
Now take 51 and subtract it by 36 and you get 15.
The monthly fee is $15.
Now you take 165 and multiply that by .30
.30 * 165 = $49.50
Then you take $49.50 and add the $15 monthly fee
$49.50 + $15 = $64.50
The cost for October is $64.50.
Hope this helps!!
