SOLUTION: Sara and Joan were able to clean the attic in 10 hours together. It takes Joan 11 hours to complete the job alone. Without help, how long would it take sara to complete this job?

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Question 903325: Sara and Joan were able to clean the attic in 10 hours together. It takes Joan 11 hours to complete the job alone. Without help, how long would it take sara to complete this job?
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
rate for A alone 11
rate for A & B together 10
1/a+1/b=1/x
1/11+1/b=1/10
1/b=1/10-1/11
1/b=11/110-10/110
1/b=1/110
1/b=1/110
b=110
rate for B alone 110
check
1/11+1/110=1/10
110/1210+11/1210=1/10
121/1210=1/10
ok