document.write( "Question 410339: one pipe can fill a tank in 3 minutes and a second pipe can fill the same tank in 7 minutes. how long will it take the two pipes to fill up this tank together? \n" ); document.write( "

Algebra.Com's Answer #288575 by josmiceli(19441) $\"\"$ $\"About$

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Add the rates of filling:
\n" ); document.write( "(1 tank filled/3 min) + (1 tank filled/7 min) = (1 tank filled / x min)
\n" ); document.write( " $\"1%2F3+%2B++1%2F7+=+1%2Fx\"$
\n" ); document.write( "Multiply both sides by $\"21x%7D%7D%0D%0A%7B%7B%7B7x+%2B+3x+=+21\"$
\n" ); document.write( " $\"10x+=+21\"$
\n" ); document.write( " $\"x+=+2.1\"$
\n" ); document.write( "both pipes together take 2.1 minutes
\n" ); document.write( "check answer:
\n" ); document.write( " $\".3333+%2B+.14286+=+.47619\"$
\n" ); document.write( " $\"1%2F2.1+=+.47619\"$
\n" ); document.write( "OK \n" ); document.write( "

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