Answer:
the person entering the room is 10 years old
Step-by-step explanation:
x / 5 = 40
x = 40 * 5
x = 200
so the total of all the ages of 5 people is 200
x/ 6 = 35
x = 35 * 6
x = 210
the total of all the ages of 6 people would have to be 210 for there to be a mean age of 35
therefore, a ten year old kid entering the room, will make up the difference
