SOLUTION: Working together, Sarah and Heidi can clean the garage in 6 hours. If they work alone, it takes Heidi 9 hours longer than it takes Sarah. How long would it take Heidi to clean the
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Question 990269: Working together, Sarah and Heidi can clean the garage in 6 hours. If they work alone, it takes Heidi 9 hours longer than it takes Sarah. How long would it take Heidi to clean the garage alone?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Add their rates of cleaning to get rate
working together
[ 1 garage cleaned ] / [ t hrs ] = Sarah's rate
[ 1 garage cleaned ] / [ t + 9 hrs ] = Heidi's rate
[ 1 garage cleaned ] / [ 6 hrs ] = their rate working together
-------------------------
Multiply both sides by
I notice that
and , so
( can't have , time can't be negative )
and
It will take Heidi 18 hrs to clean garage working alone
-----------------
check:
OK
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