SOLUTION: An old machine requires three times as many hours to complete a job as a new machine. When both machines work together, they require 9 hours to complete a job. How many hours would

Algebra ->  Rate-of-work-word-problems -> SOLUTION: An old machine requires three times as many hours to complete a job as a new machine. When both machines work together, they require 9 hours to complete a job. How many hours would      Log On


   

Question 457901: An old machine requires three times as many hours to complete a job as a new machine. When both machines work together, they require 9 hours to complete a job. How many hours would it take the new machine to finish the job operating alone?
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
o=3n
9/n+9/o=1
n=12 o=36
The new machine can do it in 12 hours working alone.