250 rpm means that the front gear has turned 250 rpm. Because the number of teeth of the front gear is twice that of the rear gear, that is to say, the front gear rotates 250*32 teeth, and the rear gear rotates 500 times, that is, 500* 16 teeth. If you want to drive with the same number of teeth. Because the number of revolutions of the rear gear is the same as that of the rear wheel, the rear wheel also rotates 500 times. The distance traveled by the rear wheel once turns is the circumference of the rear wheel, so the distance of 500 turns is π*0.48*500=240π meters. That is, her home is 240π meters away from school, which is about 754 meters.