document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=110487>Question 110487</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The Gold River's current is 6 mph. A boat travels 50 miles downstream in the same time that it takes to travel 30 miles upstream. 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 #80530 by </B><A HREF=/tutors/aboutme.mpl?userid=ptaylor><B>ptaylor(2198)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ptaylor><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=ptaylor><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=80530\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let r=rate (speed) of the boat in still water\r<BR>\n" );
document.write( "\n" );
document.write( "distance(d) = rate(r) times time(t) or d=rt; r=d/t and t=d/r\r<BR>\n" );
document.write( "\n" );
document.write( "rate upstream=(r-6)<BR>\n" );
document.write( "rate downstream=(r+6)\r<BR>\n" );
document.write( "\n" );
document.write( "We are told that time upstream=time downstream\r<BR>\n" );
document.write( "\n" );
document.write( "time upstream=30/(r-6)<BR>\n" );
document.write( "time downstream=50/(r+6)\r<BR>\n" );
document.write( "\n" );
document.write( "So our equation to solve is:\r<BR>\n" );
document.write( "\n" );
document.write( "30/(r-6)=50/(r+6)  multiply both sides by (r+6)(r-6) or cross-multiply\r<BR>\n" );
document.write( "\n" );
document.write( "30(r+6)=50(r-6)  get rid of parens (distributive law)<BR>\n" );
document.write( "30r+180=50r-300  subtract 50r and also 180 from both sides\r<BR>\n" );
document.write( "\n" );
document.write( "30r-50r+180-180=50r-50r-300-180  collect like terms\r<BR>\n" );
document.write( "\n" );
document.write( "-20r=-480  divide both sides by -20<BR>\n" );
document.write( "r=24 mph---------------------rate (speed) in still water\r<BR>\n" );
document.write( "\n" );
document.write( "CK<BR>\n" );
document.write( "30/(24-6)=50/(24+6)<BR>\n" );
document.write( "30/18=50/30<BR>\n" );
document.write( "5/3=5/3\r<BR>\n" );
document.write( "\n" );
document.write( "Hope this helps---ptaylor </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );