document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=347407>Question 347407</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A boat travels 12 miles up the Mississippi River and 12 miles back down river in a total of eight hours. The rate of the boat in still water is four miles per hour. Find the speed of the current. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #248409 by </B><A HREF=/tutors/aboutme.mpl?userid=mananth><B>mananth(16946)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=mananth><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=mananth><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=248409\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> let speed of current be xmph<BR>\n" );
document.write( "downstream speed = x+4 mph<BR>\n" );
document.write( "upstream speed = 4-x mph\r<BR>\n" );
document.write( "\n" );
document.write( "Time downstream = 12/(x+4)<BR>\n" );
document.write( "Time upstream = 12/(4-x)<BR>\n" );
document.write( "....<BR>\n" );
document.write( "12/(x+4)+12/(4-x)=8<BR>\n" );
document.write( "LCD = (x+4)(4-x)<BR>\n" );
document.write( "12(4-x)+12(x+4)/(x+4)(4-x)=8<BR>\n" );
document.write( "-12x+48+12x+48 = 8(16-x^2)<BR>\n" );
document.write( "96=128 8x^2<BR>\n" );
document.write( "8x^2=128-96<BR>\n" );
document.write( "8x^2=32<BR>\n" );
document.write( "x^2=4<BR>\n" );
document.write( "x= 2 mph the current speed. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );