Question 641527
Maria lights two candles of equal length at the same time.
 One candle takes 6 hours to burn out and the other takes 9.
 How much time will pass until the slower-burning candle is exactly
 twice as long as the faster-burning candle?
:
It will be easier if we assign a length to the candle, 18" is a good value
then
One candle burns 18/6 = 3" per hr
Other candle burns 18/9 = 2" per hr
:
Let t = time for this to happen
18 - 2t = 2(18 - 3t)
18 - 2t = 36 - 6t
-2t + 6t = 36 - 18
4t = 18
t = 18/4
t = 4{{{1/2}}} hrs