Become Smarter

A boy always asks for Rs.10 from his mother.

So his mother questioned the boy on why he kept asking for Rs.10.

The boy replied that his friend told him that
"If you eat Rs.10 worth of peanuts a day you would become smarter."

Quickly his mother gave him Rs.50.

The boy asks “Why Rs.50”, and the mother replied,

Buy Rs.10 of peanut for yourself and buy peanuts for your father with the balance.”