document.write( "Question 915624: A pipe can fill a tank in 30 minutes. A second pipe can fill the same tank in 20 minutes. A drain can empty the tank in 15 minutes. If you left the drain open, how long will it take to fill the tank with both pipes open? \n" ); document.write( "

Algebra.Com's Answer #555683 by josmiceli(19441) $\"\"$ $\"About$

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Add the rates of filling and subtract
\n" ); document.write( "the rate of draining
\n" ); document.write( " $\"+1%2F30+%2B+1%2F20+-+1%2F15+=+1%2Ft+\"$
\n" ); document.write( "Multiply both sides by $\"+60t+\"$
\n" ); document.write( " $\"+2t+%2B+3t+-+4t+=+60+\"$
\n" ); document.write( " $\"+t+=+60+\"$
\n" ); document.write( "It will take 1 hour with both filling pipes
\n" ); document.write( "open and the drain open \n" ); document.write( "

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