Question 25
David’s father picks him up from school every evening at 6 pm. One day, David was dismissed early at 5 pm. He walked home taking the same route that his father usually drives. When he met his father along the way he boarded the car and returned home 50 minutes earlier than usual. Given that his father drove at a constant speed and planned to reach the school at 6 pm sharp, how long, in minutes, had he walked before he was picked up by his father?