document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=179618>Question 179618</A>: <I><SPAN STYLE=\"word-break: break-all;\">  The Hudson River flows at a rate of 5 miles per hour. A patrol boat travels 40 miles upriver , and returns in a total time of 6 hours. What is the speed of the boat in still water?<BR>\n" );
document.write( " I have figured the distance is 40 miles with a speed of r-5 upstream and r in still water, and the total time is 6 hours but I still can not figure out how to write the equation and solve it.  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #134564 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=134564\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The Hudson River flows at a rate of 5 miles per hour. A patrol boat travels 40 miles upriver , and returns in a total time of 6 hours. What is the speed of the boat in still water?<BR>\n" );
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document.write( "Upriver DATA:<BR>\n" );
document.write( "distance = 40 miles ; rate = b - 5 ; time = d/r = 40/(b-5)<BR>\n" );
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document.write( "Downriver DATA:<BR>\n" );
document.write( "distance = 40 miles : rate = b + 5 ; time = 40/(b+5)<BR>\n" );
document.write( "----------------------<BR>\n" );
document.write( "Equation:<BR>\n" );
document.write( "time + time = 6 hrs<BR>\n" );
document.write( "40/(b-5) + 40/(b+5) = 6\r<BR>\n" );
document.write( "\n" );
document.write( "40(b+5) + 40(b-5) = 6(b^2-25)\r<BR>\n" );
document.write( "\n" );
document.write( "80b = 6b^2 - 150<BR>\n" );
document.write( "Rearrange:<BR>\n" );
document.write( "3b^2 - 40b -150 = 0<BR>\n" );
document.write( "------------------------------<BR>\n" );
document.write( "positive solution:<BR>\n" );
document.write( "b = [40 + sqrt(40^2 - (4*3*-150)]/6\r<BR>\n" );
document.write( "\n" );
document.write( "b = 23.05 mph (boat speed in still water)<BR>\n" );
document.write( "============================================<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );