<PRE><B>Question 1128135</B>
 people are sitting in a room. When an 80 year old enters the room, the average age of the people in the room doubles.
 What was the average age of the six people originally sitting in the room?
:
a = average age of the original six peaple
then
2a = average when the old guy toddles in
:
{{{((6a + 80))/7}}} = 2a
6a + 80 = 7(2a)
6a + 80 = 14a 
80 = 14a - 6a
80 = 8a
a = 10 yrs</PRE>