Walking to School (Solve multiplicative comparison word problems involving finding the size of the group using bar models)

Sara walks from her house to school every day. Lilly also walks to school from her house every day. The distance from Lilly's house to the school is 3 times longer than the distance from Sara's house to school. If Lilly's house is 900 feet from the school. How long does Sara have to walk from her house to school?