document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=184212>Question 184212</A>: <I><SPAN STYLE=\"word-break: break-all;\"> During a work-out session, Mark either ran at a speed of 7MPH or walked at a speed of 3MPH.  He completed 20 miles in 3 hours.     Please help me.    \r<BR>\n" );
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document.write( "1. Let r represent the number of miles Mark ran and w respresent the number of miles Mark walked.  Write a system of equations that represents the situation.\r<BR>\n" );
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document.write( "2.Solve the system of equations to find how much time Mark spent running.<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #138261 by </B><A HREF=/tutors/aboutme.mpl?userid=scott8148><B>scott8148(6628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=scott8148><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=scott8148><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=138261\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> the total distance is 20 mi, so r+w=20 ... and w=20-r\r<BR>\n" );
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document.write( "the total time is 3 hr ... since rate times time equals distance, time equals distance divided by rate\r<BR>\n" );
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document.write( "(r/7)+(w/3)=3\r<BR>\n" );
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document.write( "substituting ... (r/7)+((20-r)/3)=3\r<BR>\n" );
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document.write( "subtracting 20/3 ... (r/7)-(r/3)=-11/3\r<BR>\n" );
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document.write( "multiplying by 21 (LCD) ... 3r-7r=-77 ... -4r=-77\r<BR>\n" );
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document.write( "dividing by -4 ... r=77/4\r<BR>\n" );
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document.write( "since time equals distance divided by rate, Mark's running time is (77/4)/7 or 11/4 hr (2hr45min) </SPAN>\n" );
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