<PRE><B>Question 79426</B>
Arlene and AJ are Chemist. AJ can do an emulsion polymerization experiment in 10 hours. If AJ and Arlene work together they can do the experiment in 6 hours. How long will it take Arlene working by herself to do the experiment?
:
Let t = time for Ar to do the job by herself
:
Let the completed job = 1
:
A simple equation:
:
{{{6/10}}} + {{{6/t}}} = 1
:
Mult eq by 10t to get rid of the denominators, you then have:
6t + 6(10) = 10t
:
6t - 10t = -60
:
-4t = -60
t = -60/-4
t = + 15 hrs Ar by herself:
:
:
Check: 
6/10 + 6/15 =
3/5 + 2/5 = 1</PRE>