document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1099112>Question 1099112</A>: <I><SPAN STYLE=\"word-break: break-all;\"> On a weekend&#8203; outing, Carlos rents a motorboat for 10 hours to travel down the river and back. The rental operator tells him to go for 4 hours&#8203; downstream, leaving 6 hours to return upstream.\r<BR>\n" );
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document.write( "If the river current flows at a speed of 5 mph, how fast must Carlos travel in order to return in 10 hours? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #713509 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><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=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=713509\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> rate * time = distance.\r<BR>\n" );
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document.write( "let r = rate<BR>\n" );
document.write( "time is in hours<BR>\n" );
document.write( "distance is in miles\r<BR>\n" );
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document.write( "going downstream, the formula becomes (r+5)*4 = distance downstream<BR>\n" );
document.write( "going upstream, the formula becomes (r-5) * 6 = distance upstream\r<BR>\n" );
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document.write( "the distance downstream is the same as the distance upstream.\r<BR>\n" );
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document.write( "therefore (r+5)*4 = (r-5)*6<BR>\n" );
document.write( "simplify to get 4r+20 = 6r-30<BR>\n" );
document.write( "subtract 4r from both sides of this equation and add 30 to both sides of this equation to get 50 = 2r<BR>\n" );
document.write( "solve for r to get r = 25.\r<BR>\n" );
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document.write( "his boat needs to travel at 25 miles per hour.\r<BR>\n" );
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document.write( "going downstream, the stream adds 5 miles per hour to that for a total of 30 miles per hour for 4 hours to equal a distance of 120 miles.\r<BR>\n" );
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document.write( "coming back upstream, the stream subtracts 5 miles per hour from that for a total of 20 miles per hour for 6 hours to equal a total distance of 120 miles.\r<BR>\n" );
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document.write( "carlos needs to travel 25 miles per hour to go downstream and come back upstream in 10 hours.\r<BR>\n" );
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document.write( "that's what i get.\r<BR>\n" );
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document.write( " </SPAN>\n" );
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