Nandini’s house is 
km from her school. She walked some distance and then took a bus for 
km to reach the school. How far did she walk?
It is given in the question that,
Total distance = 
km
Distance for which Nandini took bus = 
km
Therefore,
Distance for which she walked = Total distance – Distance for which Nandini took bus
= 
– 
= 
= 
= 
= 
km
20