document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1011286>Question 1011286</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The rate of a boat in still water is 7km/hr. If the boat can travel 30km downstream in the same time it can travel 12 km upstream, find the rate of the river current.\r<BR>\n" );
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document.write( "Is there a formula for this kind of question? Please help! </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #626898 by </B><A HREF=/tutors/aboutme.mpl?userid=josmiceli><B>josmiceli(19441)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josmiceli><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=josmiceli><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=626898\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> It's not really a \"formula\"<BR>\n" );
document.write( "It's just catching on to a method<BR>\n" );
document.write( "Just use [ distance ] = [ rate ] x [ time ]<BR>\n" );
document.write( "--------------------------<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+c+ ALIGN=MIDDLE  ALT=\"+c+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = the rate of the current in km/hr<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+7+%2B+c+ ALIGN=MIDDLE  ALT=\"+7+%2B+c+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = rate of the boat going downstream<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+7+-+c+ ALIGN=MIDDLE  ALT=\"+7+-+c+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = rate of the boat going upstream<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+ ALIGN=MIDDLE  ALT=\"+t+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = time in hrs for going either upstream or downstream<BR>\n" );
document.write( "------------------------------------<BR>\n" );
document.write( "Equation for going downstream:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+30+=+%28+7+%2B+c+%29%2At+ ALIGN=MIDDLE  ALT=\"+30+=+%28+7+%2B+c+%29%2At+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Equation for going upstream:<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+12+=+%28+7+-+c+%29%2At+ ALIGN=MIDDLE  ALT=\"+12+=+%28+7+-+c+%29%2At+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "----------------------------<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+30+%2F+%28+7+%2B+c+%29+ ALIGN=MIDDLE  ALT=\"+t+=+30+%2F+%28+7+%2B+c+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Substitute this into (2)<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+12+=+%28+7+-+c+%29%2A%28+30+%2F+%28+7+%2B+c+%29+%29+ ALIGN=MIDDLE  ALT=\"+12+=+%28+7+-+c+%29%2A%28+30+%2F+%28+7+%2B+c+%29+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Multiply both sides by <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+7+%2B+c+ ALIGN=MIDDLE  ALT=\"+7+%2B+c+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+12%2A%28+7+%2B+c+%29+=+30%2A%28+7+-+c+%29+ ALIGN=MIDDLE  ALT=\"+12%2A%28+7+%2B+c+%29+=+30%2A%28+7+-+c+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+84+%2B+12c+=+210+-+30c+ ALIGN=MIDDLE  ALT=\"+84+%2B+12c+=+210+-+30c+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+42c+=+126+ ALIGN=MIDDLE  ALT=\"+42c+=+126+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+c+=+3+ ALIGN=MIDDLE  ALT=\"+c+=+3+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The rate of the current is 3 km/hr<BR>\n" );
document.write( "-----------------------------<BR>\n" );
document.write( "check:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+30+=+%28+7+%2B+c+%29%2At+ ALIGN=MIDDLE  ALT=\"+30+=+%28+7+%2B+c+%29%2At+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+30+=+%28+7+%2B3+%29%2At+ ALIGN=MIDDLE  ALT=\"+30+=+%28+7+%2B3+%29%2At+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+30+=+10t+ ALIGN=MIDDLE  ALT=\"+30+=+10t+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+3+ ALIGN=MIDDLE  ALT=\"+t+=+3+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "and<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+12+=+%28+7+-+c+%29%2At+ ALIGN=MIDDLE  ALT=\"+12+=+%28+7+-+c+%29%2At+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+12+=+%28+7+-+3+%29%2At+ ALIGN=MIDDLE  ALT=\"+12+=+%28+7+-+3+%29%2At+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+12+=+4t+ ALIGN=MIDDLE  ALT=\"+12+=+4t+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+3+ ALIGN=MIDDLE  ALT=\"+t+=+3+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "OK </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );