Question 1140982
Together, rate is {{{1/4}}}.
Old pump, rate is {{{1/9}}}.
Newer pump, rate is unknown, {{{1/x}}}.


{{{1/9+1/x=1/4}}}---------solve this for x.


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x IS THE TIME FOR THE NEWER PUMP TO DO THE JOB BY ITSELF.
COMBINED RATE IS SUM OF THE INDIVIDUAL RATES.
SOLVE THE EQUATION FOR x.