Mr. Smith takes the train daily from his work in the city back to the suburb where he lives and is met at the station by his chauffeur, who drives
him home. One day Mr. Smith finishes his work earlier than usual and arrives in his suburb one hour earlier than usual. He then walks toward his home from the station, and meets his chauffeur (who was not aware of Mr. Smith's early leaving time) on the way. The chauffeur stops and takes Mr. Smith home; this brings Mr. Smith home 10 minutes earlier than usual. Disregarding time for stopping and picking up, and assuming that the chauffeur normally arrives at the station at the same moment as Mr. Smith, for how long (in minutes) did Mr. Smith walk?
any help please?