document.write( "Question 548634: A pool can be filled in 12 hours using pipe A, or in 30 hours using pipe B. If both pipes are used, how long it will take to fill the pool? \n" ); document.write( "

Algebra.Com's Answer #357121 by Earlsdon(6294) $\"\"$ $\"About$

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Let x = the number of hours to fill the pool.
\n" ); document.write( "The rate of filling for pipe A is $\"x%2F12\"$ and for pipe B is $\"x%2F30\"$
\n" ); document.write( "The rate of filling for both A and B is:
\n" ); document.write( " $\"x%2F12%2Bx%2F30+=+7x%2F60\"$ so to fill the pool, set this equal to 1 and solve for x:
\n" ); document.write( " $\"7x%2F60+=+1\"$ Multiply both sides by the multiplicative inverse of $\"7%2F60\"$ which is $\"60%2F7\"$ to get:
\n" ); document.write( " $\"x+=+60%2F7\"$ hours or
\n" ); document.write( " $\"x+=+8\"$ hours and $\"34.3\"$ minutes.\r
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