Decisions decisions

I am contemplating on watching a one year old little girl all day on Fridays and sometimes on Mondays and Wednesdays. I know I would be able to handle it and it would be nice to be able to help someone out and make some money doing it. It would also give my kiddos someone else to play with. I just hate to think that on the days I watch her that means I am gonna be stuck at home for sure. What if the little girl is a little devil. I am not even sure how to charge her and be fair about it. I know the going rate is $120 a week at day cares around here so would that mean I charge $20 a day? Maybe Travis can help me make up my mind.