document.write( "Question 507347: One pipe fills a storage tank in 30 hours. A second pipe fills the same tank in 45 hours. When a third pipe is added and all three pipes are used to fill the tank it only 9 hours. Find how long it takes the third pipe to do the job. \n" ); document.write( "
Algebra.Com's Answer #340447 by lwsshak3(11628)\"\" \"About 
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One pipe fills a storage tank in 30 hours. A second pipe fills the same tank in 45 hours. When a third pipe is added and all three pipes are used to fill the tank it only 9 hours. Find how long it takes the third pipe to do the job.
\n" ); document.write( "**
\n" ); document.write( "Work rates:
\n" ); document.write( "1st pipe: 1/30
\n" ); document.write( "2nd pipe: 1/45
\n" ); document.write( "3rd pipe: 1/x
\n" ); document.write( "All three pipes used: 1/9
\n" ); document.write( "..
\n" ); document.write( "sum of individual rates = rate when all working together
\n" ); document.write( "..
\n" ); document.write( "1/30+1/45/+1/x=1/9
\n" ); document.write( "1/x=1/9-1/30-1/45
\n" ); document.write( "LCD:90x
\n" ); document.write( "90=10x-3x-2x=5x
\n" ); document.write( "5x=90
\n" ); document.write( "x=18
\n" ); document.write( "ans:
\n" ); document.write( "It would take the 3d pipe 18 hours to do the job alone \n" ); document.write( "
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