MIND TEASERS

Sam used to go to his office by bus. His friend used to 
receive him every evening at 05:00p.m. from the bus stand 
and then leave him at 05:30p.m. at his house. This friend 
was very punctual. On a particular day Sam reached the bus 
stand half an hour earlier than the usual time. He did not 
wait for his friend at the bus stand. and without wasting 
any time started to words this house on an autorickshaw. In 
the way at the supermarket he saw the car which his friend 
was driving. He would have reached the bus stand. at 
05:00p.m. as usual. So Sam without losing any time sat in 
the car and at 5.20p.m. he was at his house. Please tell 
how much time did Sam spend in the autorickshaw.

Solution--Sam spent a total of 25 minutes travelling in the 
autorickshaw.
Sam met his friend at the supermarket and the total time 
saved in reaching his house was only ten minutes. This time 
who would have been used by the car from the supermarket to 
the bus stand and then from a bus stand to the supermarket. 
So the friend had met Sam at 4.55 p.m.