SOLUTION: A woman can do a certain job in 5 hours. Her daughter can do it in 7 hours. After the woman and her daughter have been working for an hour, the woman's husband joined them. The thr

Algebra ->  Rate-of-work-word-problems -> SOLUTION: A woman can do a certain job in 5 hours. Her daughter can do it in 7 hours. After the woman and her daughter have been working for an hour, the woman's husband joined them. The thr      Log On


   

Question 829894: A woman can do a certain job in 5 hours. Her daughter can do it in 7 hours. After the woman and her daughter have been working for an hour, the woman's husband joined them. The three completed the job in 4 more hours. How long would it take the husband to finish the same job alone?
Please help.
Answer by josgarithmetic(39615) About Me  (Show Source):
You can put this solution on YOUR website!
These are their rates in jobs per hour:
Woman, 1/5
Daughter, 1/7
Husband, 1/x

Uniform rates problems are as R%2At=j: Rate, time, job.

1 hour woman & daughter together.
4 hours woman & daughter & husband.

highlight%28%281%2F5%2B1%2F7%29%2A1%2B%281%2F5%2B1%2F7%2B1%2Fx%29%2A4=1%29 ----- that is the equation in raw form for the one job to become done. Solve for x.


To begin solving that equation, multiply left and right members by the simplest common denominator, 37x. This will clear the fractions. You do the rest.