KöMaL 2006 B3892

The president of the Pyramid Bank lives in a fancy residential district outside the city. On weekdays, he is driven to the city in a car that leaves the bank in the city at the same time every morning, picks up the president and they arrive at the bank exactly when it opens. One morning, the driver called the president to say that something was wrong with the car and he would be late. So the president left home one hour earlier than usual on foot. Meanwhile, the driver fixed the car and still managed to leave the city at the usual time. He met the bank president on the way, picked him up, and they arrived at the bank 20 minutes before opening. How long did the president walk? (Assume that the speed of the car is constant, and picking up a passenger does not take any time.)