Two brothers, Jack and Joe, were born in May. One was born in 1932, and the other, a year later. Each brother owned a watch, which was previously possessed by their father.
Considering their age, the watches worked pretty well.
Nonetheless, one watch gained ten seconds per hour, while the other lost ten seconds per hour.
On a day of January, they set their watches at 12:00 PM. Joe said: "Hey, Jack, listen. The next time that our watches will both show exactly the same time, it will be on your 47th birthday!" Jack was surprised at first, but nodded.
Who is older, and what year is it?