document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=177764>Question 177764</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Linear System<BR>\n" );
document.write( "A boat took 5 h to travel 60km up a river, against the current. The return trip took 3 h. Find the speed of the boat in still water and 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 #132880 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=132880\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A boat took 5 h to travel 60km up a river, against the current. The return trip<BR>\n" );
document.write( " took 3 h. Find the speed of the boat in still water and the speed of the current.<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Let x = boat speed in still water<BR>\n" );
document.write( "Let y = current speed<BR>\n" );
document.write( "then<BR>\n" );
document.write( "(x-y) = effective speed up-stream<BR>\n" );
document.write( "and<BR>\n" );
document.write( "(x+y) = effective speed down stream<BR>\n" );
document.write( ":<BR>\n" );
document.write( "write two distance equations:<BR>\n" );
document.write( "dist = time * speed<BR>\n" );
document.write( ":<BR>\n" );
document.write( "5(x-y) = 60<BR>\n" );
document.write( "3(x+y) = 60<BR>\n" );
document.write( "simplify both equations, divide the 1st one by 5, the 2nd one by 3 and you have:<BR>\n" );
document.write( "x - y = 12<BR>\n" );
document.write( "x + y = 20<BR>\n" );
document.write( "-------------addition eliminates y, find x:<BR>\n" );
document.write( "2x = 32<BR>\n" );
document.write( "x = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=32%2F2 ALIGN=MIDDLE  ALT=\"32%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "x = 16 km/hr boat speed in still water<BR>\n" );
document.write( "then<BR>\n" );
document.write( "16 + y = 20<BR>\n" );
document.write( "y = 20 - 16<BR>\n" );
document.write( "y = 4 km/hr current speet<BR>\n" );
document.write( ":<BR>\n" );
document.write( ":<BR>\n" );
document.write( "check solution by finding the dist of both<BR>\n" );
document.write( "5(16-4) = 60<BR>\n" );
document.write( "3(16+4) = 60<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );