Question 1099571
A tap can fill a tank in 6 mins 
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So the 1st tap's filling rate is {{{matrix(1,2,1,tank)/matrix(1,2,6,min)}}} or {{{matrix(1,2,1/6,tank/min)}}}
</pre>
and another can fill the same tank in 8 mins .
<pre>
So the 2nd tap's filling rate is {{{matrix(1,2,1,tank)/matrix(1,2,8,min)}}} or {{{matrix(1,2,1/8,tank/min)}}}
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How long will it take to fill the tank if the two taps were opened at the same time?
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Let the answer be x mins.

So together they can fill 1 tank in x minutes

So their combined filling rate is {{{matrix(1,2,1,tank)/matrix(1,2,x,min)}}} or {{{matrix(1,2,1/x,tank/min)}}}

Their combined filling rate must be equal to the sum of their 
filling rates:

{{{matrix(1,2,1/6,tank/min)}}}{{{""+""}}}{{{matrix(1,2,1/8,tank/min)}}}{{{""=""}}}{{{matrix(1,2,1/x,tank/min)}}}

{{{1/6}}}{{{""+""}}}{{{1/8}}}{{{""=""}}}{{{1/x}}}

Multiply through by the LCD of 24x

{{{4x}}}{{{""+""}}}{{{3x}}}{{{""=""}}}{{{24}}}

{{{7x}}}{{{""=""}}}{{{24}}}

{{{x}}}{{{""=""}}}{{{24/7}}}

{{{x}}}{{{""=""}}}{{{3&3/7}}}{{{minutes}}}

Edwin</pre>