Teacher: 2 aur 2 char hote hai to yeah batao ki mere ghar ki tanki me kitna pani?
Student (to himself): yeh kya question hai?
.
.
.
then he says: madam the answer is 80 ltrs..
.
.
.
Teacher: You are right. Tumhe kaise pata?
.
.
.
Student: kyuki hamare ghar pe aaj aaloo ki subzee bani thi.