Subject: mathqa
Question: exactly 3 / 7 of the people in the room are under the age of 21 , and exactly 5 / 12 of the people in the room are over the age of 65 . if the total number of the people in the room is greater than 50 and less than 100 , how many people in the room are under the age of 21 ?
Option: 
A: 65
B: 36
C: 35
D: 60
Answer: B