SOLUTION: Sam and Dave can mow the lawn in 60 minutes if they work together. If Dave works twice as fast as Sam, how long does it take same to mow the lawn alone?
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Question 857118: Sam and Dave can mow the lawn in 60 minutes if they work together. If Dave works twice as fast as Sam, how long does it take same to mow the lawn alone? Answer by jim_thompson5910(35256) (Show Source):
You can put this solution on YOUR website! Since "Dave works twice as fast as Sam", this means that Sam takes twice as long. So if x = time for David to do the job alone, then 2x = time for Sam to do the job alone
1/x + 1/(2x) = 1/60
2/(2x) + 1/(2x) = 1/60
(2+1)/(2x) = 1/60
3/(2x) = 1/60
3*60 = 2x*1
180 = 2x
180/2 = x
90 = x
x = 90
2x = 2*90 = 180
So Dave takes 90 minutes and Sam takes 180 minutes
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