A harried parent leaves his house during rush-hour each weekday to pick up his wife at the train station. From the train station, he then goes to pick up his child at school, before returning home. His house, the station, and the school are an equal distance of 1 mile from each other (on an imaginary equilateral triangle). He makes the trip in 15 minutes, during rush hour traffic. At that time of day, he averages 10 mph slower between the station and the school than on the other 2 legs of the trip. How fast is his speed between his house and the station? Please give explanation and steps.