How Long Was He Walking?

Question

Every day, Jack arrives at the train station from work at 5 pm.
His wife leaves home in her car to meet him there at exactly 5 pm, and drives him home. One day, Jack gets to the station an hour early, and starts walking home, until his wife meets him on the road. They get home 30 minutes earlier than usual. How long was he walking?

Distances are unspecified. Speeds are unspecified, but constant.

Give a number which represents the answer in minutes.

Answer 1

45 minutes
.
They arrive 30 minutes earlier at the house. This 30 minutes is divided equally between the drive from the house to Jack and back from Jack to the house. Thus the drive from the house to Jack is 15 minutes shorter than normal.
Normally his wife would meet Jack at the station at 5pm. She now meets Jack 15 minutes earlier, thus at 4:45pm. Jack started walking at 4pm, so he has been walking for 45 minutes.