SOLUTION: Stan and Hilda can mow the lawn in 40 min if they work together. If Hilda works twice as fast as Stan, how long does it take Stan to mow the lawn alone?

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Question 53530: Stan and Hilda can mow the lawn in 40 min if they work together. If Hilda works twice as fast as Stan, how long does it take Stan to mow the lawn alone?
Answer by funmath(2933) About Me  (Show Source):
You can put this solution on YOUR website!
With this kind of problem, there is more than one way to do it---I can think of 4 ways right now. So don't be upset if your teacher does this a different way in class. This is just one of the ways you can attack this problem.
Another way of looking at Hilda being twice as fast as Stan is to say that Stan takes twice as long to finish the job.
Let the amount of time it takes Hilda to do the job=x.
Let the amount of time it takes Stan to do the job=2x.
Then your problem is:
1%2Fx%2B1%2F2x=1%2F40
Multiply both sides of the equation by the LCD, in this case the LCD is 40x.
40x%281%2Fx%2B1%2F2x%29=40x%281%2F40%29
40x%2Fx%2B40x%2F2x=40x%2F40
40%2B20=x
60=x
x=60 min (1 hr) is the time it taks Hilda to do the job.
2x=2(60)=120 min (2 hr) is the time it takes Stan to do the job.