SOLUTION: A can do a job in 9 days, A and B together can complete a job in 5 days. How long will it take B alone to complete it?

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Question 271958: A can do a job in 9 days, A and B together can complete a job in 5 days. How long will it take B alone to complete it?

Found 2 solutions by stanbon, richwmiller:
Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website!
A Can do a job in 9 days, A and B together can complete a job in 5 days. How long will B Alone can complete it?
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A rate: 1/9 job/day
Together rate: 1/5 job/day
B rate = 1/x job/day
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Equation:
rate + rate = together rate
1/9 + 1/x = 1/5
1/x = 1/5 - 1/9
1/x = 4/45
x = 45/4
x = 11 1/4 days (Time for B to do the job alone)
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Cheers,
Stan H.

Answer by richwmiller(17219) (Show Source):
You can put this solution on YOUR website!
A can do 1/9 in one day and 5/9 in 5 days.
a+b=1
5/9+b=1
b=4/9
in 5 days b does 4/9 of the job
5/x=4/9
4x=45
x=45/4=11.25
b can complete it alone in 11.25 days.
5/9+5/11.25=1
or
d/9+d/x=1
d=5
5/9+5/x=1
5/b=4/9
check
x/a+x/b=1
a=9 and b=11.25
x=5
ok