document.write( "Question 885105: if 2 people work at washing 5 cars and one can do all 5 on their own in 36 minutes and the other can do all 5 on their own in 42 minutes, how long does it take to wash all 5 working together? \n" ); document.write( "

Algebra.Com's Answer #534924 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
Since it's only about washing 5 cars, call that 1 job
\n" ); document.write( "1st person's rate of washing:
\n" ); document.write( "( i job ) / ( 36 min )
\n" ); document.write( "2nd person's rate of washing:
\n" ); document.write( "( 1 job ) / ( 42 min )
\n" ); document.write( "--------------------------
\n" ); document.write( "Let $\"+t+\"$ = the time to finish job
\n" ); document.write( "working together
\n" ); document.write( "Add their rates of working to get
\n" ); document.write( "their rate working together
\n" ); document.write( "--------------------------
\n" ); document.write( " $\"+1%2F36+%2B+1%2F42+=+1%2Ft+\"$
\n" ); document.write( " $\"+%28+1%2F6+%29%2A%28+1%2F6+%2B+1%2F7+%29+=+1%2Ft+\"$
\n" ); document.write( " $\"+1%2F6+%2B+1%2F7+=+6%2Ft+\"$
\n" ); document.write( "Multiply both sides by $\"+42t+\"$
\n" ); document.write( " $\"+7t+%2B+6t+=+6%2A42+\"$
\n" ); document.write( " $\"+13t+=+252+\"$
\n" ); document.write( " $\"+t+=+19.3846+\"$
\n" ); document.write( "It will take them 19 and 5/13 min woking together
\n" ); document.write( "check:
\n" ); document.write( " $\"+1%2F36+%2B+1%2F42+=+1%2Ft+\"$
\n" ); document.write( " $\"+.027777+%2B+.023809+=+1%2F19.3846+\"$
\n" ); document.write( " $\"+.051587+=+.051587+\"$
\n" ); document.write( "OK\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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