You don’t know my father

Teacher: Tumhare papa 500 rupees loan lete hai. 10% interest ke hisab se woh 1 saal baad loan vapis karte hai. Batao kitne paise vapis karenge?

Bania’s son: Kuch bhi nahi.

Teacher: Tum maths nahi jante.

Banis’s son: Main toh maths janta hoon, par aap mere papa ko nahi jante.