document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=946745>Question 946745</A>: <I><SPAN STYLE=\"word-break: break-all;\"> the current of a river is 3 miles/hour. it takes a motorboat a total of 3 hours to travel 12 miles upstream and return 12 miles downstream. 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 #577576 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=577576\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> the current of a river is 3 miles/hour. it takes a motorboat a total of 3 hours to travel 12 miles upstream and return 12 miles downstream. 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+3=speed of boat downstream<BR>\n" );
document.write( "x-3=speed of boat upstream<BR>\n" );
document.write( "travel time=distance/speed<BR>\n" );
document.write( "..<BR>\n" );
document.write( "12/(x+3)+12/(x-3)=3<BR>\n" );
document.write( "lcd:(x+3)(x-3)<BR>\n" );
document.write( "12(x-3)+12(x+3)=3(x+3)(x-3)<BR>\n" );
document.write( "12x-36+12x+36=3(x^2-9)=3x^2-27<BR>\n" );
document.write( "3x^2-24x-27=0<BR>\n" );
document.write( "x^2-8x-9=0<BR>\n" );
document.write( "(x+1)(x-9)=0<BR>\n" );
document.write( "x=9<BR>\n" );
document.write( "speed of boat in still water=9 mph </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );