Funny Question

Professor:"1 Platform 2
km lambaa hai,
.
Aandhi chal rahi hai,
60km/h ki
speed se Ek Train Aayi
aur Delhi se
Mumbai ki Taraf Chali
gayi..
.
.
To Sawal ye hai ke:"
Meri Umar Kitni hai.. ??
.
.
Sab Bachhe Hairaan ho
ke 1 Doosre ki Shakal
dekhne Lagey..
.
.
ek Student ne Jawab
dene keliye haath
Uthaaya..
.

Student:" Sir Aapki Umar
42 saal hai..
.
Profesor:" Very Gud,
Lekin tumne
kaise Calculate kiya ??
.
.
Studnt:" Sir Hamare Ghar
ke paas 1 Aadmi Rehta
hai, wo AADHA pagal
hai aur Uski Umar 21
Saal
hai...