document.write( "Question 657668: Hi, could you tell me how to set up a problem like \"You can wash one window in 15 minutes and your sister can wash one window in 20 minutes. How many minutes will it take to wash 12 windows if you work together?\"
\n" ); document.write( "All I need to know is how to set it up.\r
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Algebra.Com's Answer #409982 by ankor@dixie-net.com(22740)\"\" \"About 
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You can wash one window in 15 minutes and your sister can wash one window in 20 minutes.
\n" ); document.write( " How many minutes will it take to wash 12 windows if you work together?\"
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\n" ); document.write( "Let t = time required for both of you to wash 12 windows
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\n" ); document.write( "\"t%2F15\" + \"t%2F20\" = 12
\n" ); document.write( "multiply by 60 to get rid of the denominators, results:
\n" ); document.write( "4t + 3t = 60(12)
\n" ); document.write( "7t = 720
\n" ); document.write( "t = 720/7
\n" ); document.write( "t ~ 103 minutes, or 1 hr 43 min \n" ); document.write( "
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