Base plan fee is $64.95, a $5 discount from normally $69.95.
Speed boost to 100/40 speed is $40 making up total monthly fee of $104.95 consisting of $64.95 base plan + $40 speed boost to 100/40 speed. All speed boosts get $5 bonus credit. This reduces the monthly fee froom $104.95 minus $5 to $99.95.
The combined savings each month is $10.