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Question 887380: Housecleaning. Sally can clean the house in 6 hours, and her father can clean the house in 4 hours. Sally's younger brother, Dennis, cna completely mess up the house in 8 hours. If Sally and her father clean and Dennis plays, how long will it take to clean the house?
Found 2 solutions by lwsshak3, josgarithmetic:
Answer by lwsshak3(11628)   (Show Source):
You can put this solution on YOUR website! Housecleaning. Sally can clean the house in 6 hours, and her father can clean the house in 4 hours. Sally's younger brother, Dennis, can completely mess up the house in 8 hours. If Sally and her father clean and Dennis plays, how long will it take to clean the house?
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let x= how long will it take to clean the house
1/6=Sally's work rate
1/4=father's work rate
-1/8=Dennis' work rate
1/x=work rate working together
sum of indv. work rates=work rate working together
..
lcd:24
7=24/x
x=24/7
how long will it take to clean the house=24/7 hrs
Answer by josgarithmetic(39620) (Show Source):
You can put this solution on YOUR website! The younger brother's rate is negative in regard to cleaning the house. One job is "clean the house".
 , the HOUSE per HOUR cleaning rate.
For HOURS per HOUSE,  .
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