Question 1118017
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Lupe can clean 4 houses in A  certain NUMBER OF hours. it takes susie 2 more hours to clean 4 houses. if they work together, they can clean 9 houses in 10 hours. How long does it take Lupe to clean 4 houses by herself? 
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Rates in unit of HOUSES per HOUR

LUPE, {{{4/x}}}

Susie, {{{4/(x+2)}}}

TOGETHER Lupe and Susie, {{{9/10}}}

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{{{4/x+4/(x+2)=9/10}}}-------Solve this for x.