document.write( "Question 133572: One printing machine workes twice as fast as another. When both machines are used, they can print a magazine in 3h. How many hours would each machine require to do the job alone? \n" ); document.write( "

Algebra.Com's Answer #97731 by josmiceli(19441) $\"\"$ $\"About$

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Add their rates of working
\n" ); document.write( "(1st machines rate) + (2nd machines rate) = (rate printing together)
\n" ); document.write( "Let the 1st machines rate = $\"r\"$
\n" ); document.write( "Let the 2nd machine have the faster rate, $\"2r\"$
\n" ); document.write( " $\"r+%2B+2r+=+1%2F3\"$
\n" ); document.write( "The $\"1%2F3\"$ means (1 magazine/3 hours) which is the rate printing
\n" ); document.write( "together
\n" ); document.write( " $\"3r+=+1%2F3\"$
\n" ); document.write( " $\"r+=+1%2F9\"$
\n" ); document.write( "So, the 1st machine can print 1 magazine in 9 hours
\n" ); document.write( "For the 2nd machine,
\n" ); document.write( " $\"2r+=+2%2F9\"$
\n" ); document.write( "This means (2 magazines/9 hours) or,
\n" ); document.write( "(1 magazine)/4.5 hours)
\n" ); document.write( "The 2nd machine can print 1 magazine in 4.5 hours
\n" ); document.write( "check answers:
\n" ); document.write( " $\"r+%2B+2r+=+1%2F3\"$
\n" ); document.write( " $\"1%2F9+%2B+2%2A%281%2F9%29+=+1%2F3\"$
\n" ); document.write( " $\"3%2F9+=+1%2F3\"$
\n" ); document.write( " $\"1%2F3+=+1%2F3\"$
\n" ); document.write( "OK \n" ); document.write( "

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