The teacher's house, Xiaoxue's house and the school are on the same road. It is 425 meters from the teacher's home to the school. It is 170 meters from Xiaoxue's home to the school. How many situations may there be in the location of their two families and the school? How far is it from the teacher's house to Xiaoxue's house? Please list the calculation.
老师家、小雪家和学校在同一条路上．老师家到学校有425米．小雪家到学校有170米．他们两家和学校的位置可能有多少种情况．老师家到小雪家有多远？请列式计算．
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