SOLUTION: If sally can paint a room in 9 hours, and it takes dave 5 hours to paint the same room, how long will it take them if they work together?

Algebra ->  Rate-of-work-word-problems -> SOLUTION: If sally can paint a room in 9 hours, and it takes dave 5 hours to paint the same room, how long will it take them if they work together?      Log On


   

Question 653990: If sally can paint a room in 9 hours, and it takes dave 5 hours to paint the same room, how long will it take them if they work together?
Answer by checkley79(3341) About Me  (Show Source):
You can put this solution on YOUR website!
1/9+1/5=1/X FIND A COMMON DENOMINATOR (9*5)=45
[(1*5)+(1*9)]/45=1/X
[5+9]/45=1/X
14/45=1/X CROSS MULTIPLY.
14X=45
X=45/14
X=3.2 HOURS WORKING TOGETHER.