document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=864811>Question 864811</A>: <I><SPAN STYLE=\"word-break: break-all;\"> the current of a stream moves at 5 mph. a boat travels 31 mi upstream and 31 mi down stream in a total time if 20 hours what is the speed of the boat in still water? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #521306 by </B><A HREF=/tutors/aboutme.mpl?userid=lwsshak3><B>lwsshak3(11628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=lwsshak3><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=521306\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> the current of a stream moves at 5 mph. a boat travels 31 mi upstream and 31 mi down stream in a total time if 20 hours what is the speed of the boat in still water?<BR>\n" );
document.write( "***<BR>\n" );
document.write( "let x=speed of boat in still water.<BR>\n" );
document.write( "x+5=speed of boat downstream.<BR>\n" );
document.write( "x-5=speed of boat upstream.<BR>\n" );
document.write( "travel time=distance/speed<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=31%2F%28x%2B5%29%2B31%2F%28x-5%29=20 ALIGN=MIDDLE  ALT=\"31%2F%28x%2B5%29%2B31%2F%28x-5%29=20\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "LCD:(x+5)(x-5)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=31%28x-5%29%2B31%28x%2B5%29=20%28x-5%29%28x%2B5%29 ALIGN=MIDDLE  ALT=\"31%28x-5%29%2B31%28x%2B5%29=20%28x-5%29%28x%2B5%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=31x-155%2B31x%2B155=20%28x%5E2-25%29 ALIGN=MIDDLE  ALT=\"31x-155%2B31x%2B155=20%28x%5E2-25%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=62x=20x%5E2-500%29 ALIGN=MIDDLE  ALT=\"62x=20x%5E2-500%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "20x^2-62x-500=0<BR>\n" );
document.write( "10x^2-31x-250=0<BR>\n" );
document.write( "solve for x by quadratic formula: <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+ ALIGN=MIDDLE  ALT=\"x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "a=10, b=-31, c=-250<BR>\n" );
document.write( "ans:<BR>\n" );
document.write( "x&#8776;6.78<BR>\n" );
document.write( "speed of the boat in still water? 6.78 mph </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );