Question 1029990
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A container 80cm/60cm/70cm needs to be filled up completely with water. 
Tube A supplies 24l of water per minute and Tube B supplies 18l of water per minute. 
Mr Tan fills up the container by taking turns to use both Tubes for 17minutes. 
How long does he use each of the Tubes?
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The volume of the tank is 80*60*70 = 336000 cm^3,  or 336 liters.

Let x be the time for tube A working, in minutes;

then (17-x) is the time for the tube B working.


Write an equation for the total volume

    24*x + 18*(17-x) = 336.


Simplify and find x

    24x + 306 - 18x = 336

    24x - 18x = 336 - 306

        6x    =    30

         x    =    30/6 = 5.


So, tube A worked 5 minutes;  tube B worked 17-5 = 12 minutes.    <<<---===  <U>ANSWER</U>


<U>CHECK</U>.  The total volume is  24*5 + 18*12 = 336 liters,  which is precisely correct.
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Solved.