Davis, roy, and tom are on the rowing team. each sits in a different
position (front, middle, and end) and is a different age (18, 19, and 20).
• tom and the 19-year-old do not sit in the rear.
• the person who sits in the rear is 20 years old.
• neither tom nor roy sits in the front.
who sits in the middle, and how old is he? be sure to check both answers.