document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=160125>Question 160125</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/0618803718/algebrahomeworkh>College Algebra</A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> A boat has a speed of 5 mph in still water.  The boat can travel 21 miles with the current in the same amount of time it takes to travel 9 miles against the current.  Find the rate 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 #118164 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=118164\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <BR>\n" );
document.write( "Distance(d) equals Rate(r) times Time(t) or d=rt;  r=d/t and t=d/r<BR>\n" );
document.write( "(Note: when travelling with the current, we add the speed of the current; when travelling against the current, we subtract the speed of the current)<BR>\n" );
document.write( "Let r=rate of the current<BR>\n" );
document.write( "Time travelling with the current=21/(5+r)<BR>\n" );
document.write( "Time travelling against the current=9/(5-r)\r<BR>\n" );
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document.write( "Now we are told that the above times are equal, so:\r<BR>\n" );
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document.write( "21/(5+r)=9/(5-r)  multiply each side by (5-r)(5+r) or cross multiply<BR>\n" );
document.write( "21(5-r)=9(5+r)  get rid of parens<BR>\n" );
document.write( "105-21r=45+9r subtract 105 and also 9r from each side<BR>\n" );
document.write( "105-105-21r-9r=45-105+9r-9r  collect like terms\r<BR>\n" );
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document.write( "-30r=-60  divide each side by -30<BR>\n" );
document.write( "r=2 mph---------------------------speed of the current\r<BR>\n" );
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document.write( "CK<BR>\n" );
document.write( "21/7=9/3<BR>\n" );
document.write( "3=3\r<BR>\n" );
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document.write( "Hope this helps---ptaylor\r<BR>\n" );
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document.write( " </SPAN>\n" );
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