SOLUTION: It takes a boy 30 minutes to mow the lawn, but his sister can mow it in 20 minutes. How long would it take them to mow the lawn if they worked together, using two lawn mowers?
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Question 342502: It takes a boy 30 minutes to mow the lawn, but his sister can mow it in 20 minutes. How long would it take them to mow the lawn if they worked together, using two lawn mowers?
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!
If A can do a job in x time periods, then A can do 
of the job in 1 time period. Likewise, if B can do the same job in y time periods, then B can do 
of the job in 1 time period.
So, working together, they can do
of the job in 1 time period.
Therefore, they can do the whole job in:
time periods.
John
My calculator said it, I believe it, that settles it
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