Question 1081540
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The drainage rate is 3 m^3 per minute.


I solved it mentally.



But if you want to see the equations, here they are.


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Let d = the drainage rate, in m^3/minute.
    f = the filing rate.


Then 

d - f = 1,

{{{54/f}}} - {{{54/d}}} = 9.


From the first equation, express f = d-1 and substitute it into the second equation. You will get

{{{54/(d-1)}}} - {{{54/d}}} = 9.


Solve it for d.
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