Two years of local internet service costs $685, including the installation fee of $85. what is the monthly fee?

For the monthly fee, we first have to subtract the installation fee of 85 from the total cost for two years which is 685. Why? Because an installation fee is a one time thing. You don't install every year. So less the installation fee, our internet service cost for two years is 600. To make things easier, lets get the service costs for one year. Divide 600 by 2 and you will get 300. 300 is the cost of the internet for a whole year. Divide this by 12 (12 months in a year) and you will get 25. The monthly cost is $25.