<PRE><B>Question 524142</B>
Three brothers decide to paint their house. Kevin could paint the house in 12 hours, and Nick could paint it in 15 hours. When they work together with their brother, Joe, it only takes five hours to paint the whole house. How long would it take Joe to paint the house if he worked alone?
-----
kevin rate = 1/12 job/hr
---
Nick rate = 1/15 job/hr
----
Joe rate = 1/x job/hr
----
Together rate = 1/5 job/hr
-----
Equation:
rate + rate + rate = together rate
1/12 + 1/15 + 1/x = 1/5
----
Multiply thru by 60x to get:
5x + 4x + 60 = 12x
3x = 60
x = 20 (time for Joe to do the job alone)
----
Cheers,
Stan H.
------
</PRE>