document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=91765>Question 91765</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A boat can travel 5 miles upstream and 5 miles downstream in a total of 6 hours. If the speed of the current is 2 miles per hour, 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 #66659 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=66659\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A boat can travel 5 miles upstream and 5 miles downstream in a total of 6 hours. If the speed of the current is 2 miles per hour, what is the speed of the boat in still water?<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Let s = speed in still water<BR>\n" );
document.write( "Then<BR>\n" );
document.write( "(s+2) = speed down-stream<BR>\n" );
document.write( "and<BR>\n" );
document.write( "(s-2) = speed up-stream<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Write a time equation; Time = dist/speed<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Time up-stream + time down-stream = 6 hrs<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5%2F%28%28s-2%29%29 ALIGN=MIDDLE  ALT=\"5%2F%28%28s-2%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > + <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=5%2F%28%28s%2B2%29%29 ALIGN=MIDDLE  ALT=\"5%2F%28%28s%2B2%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 6<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Multiply equation by (s-2)(s+2) and you have:<BR>\n" );
document.write( "5(s+2) + 5(s-2) = 6(s-2)(s+2)<BR>\n" );
document.write( ":<BR>\n" );
document.write( "5s + 10 + 5s - 10 = 6(s^2 - 4)<BR>\n" );
document.write( ":<BR>\n" );
document.write( "5s + 5s + 10 - 10 = 6s^2 - 24<BR>\n" );
document.write( ":<BR>\n" );
document.write( "10s = 6s^2 - 24<BR>\n" );
document.write( ":<BR>\n" );
document.write( "0 = 6s^2 - 10s - 24<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Simplify divide equation by 2 and you have:<BR>\n" );
document.write( "3s^2 - 5s - 12 = 0<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Factors to<BR>\n" );
document.write( "(3s + 4 )(s - 3) = 0<BR>\n" );
document.write( ":<BR>\n" );
document.write( "s = +3 mph in still water, (it's the positive solution we want here)<BR>\n" );
document.write( ":<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Check using time: speed upstream (3-2)= 1 mph; speed down (3+2) = 5 mph<BR>\n" );
document.write( "5/1 = 5 hrs upstream<BR>\n" );
document.write( "5/5 = 1 hr downstream<BR>\n" );
document.write( "-------------------<BR>\n" );
document.write( "total 6 hrs as given </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );