document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1050412>Question 1050412</A>: <I><SPAN STYLE=\"word-break: break-all;\"> the boat goes downstream at 13 kph<BR>\n" );
document.write( "upstream it goes three kph<BR>\n" );
document.write( "what is the speed of the current?<BR>\n" );
document.write( "It is obvious it is ten kph, but how do you put this into an equation? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #665978 by </B><A HREF=/tutors/aboutme.mpl?userid=advanced_Learner><B>advanced_Learner(501)</B></A><img src=\"/images/stars/stars-10.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=advanced_Learner><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=advanced_Learner><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=665978\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> u+v=13<BR>\n" );
document.write( "u-v=3\r<BR>\n" );
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document.write( " <TR><TD  ALIGN=MIDDLE>Solved by <A  rel=nofollow HREF=http://wiki.algebra.com/index.php/Tutoring_-_pluggable_solvers>pluggable</A> solver: <A  rel=nofollow HREF=linear_substitution.solver>SOLVE linear system by SUBSTITUTION</A></TD></TR>\n" );
document.write( "<TR><TD  ALIGN=LEFT>Solve:<BR>\n" );
document.write( "  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+system%28+%0D%0A++++1%5Cu+%2B+1%5Cv+=+13%2C%0D%0A++++1%5Cu+%2B+-1%5Cv+=+3+%29%0D%0A++ ALIGN=MIDDLE  ALT=\"+system%28+%0D%0A++++1%5Cu+%2B+1%5Cv+=+13%2C%0D%0A++++1%5Cu+%2B+-1%5Cv+=+3+%29%0D%0A++\"   DISABLED_style= \"max-width:90%; height:auto;\" >We'll use substitution. After moving 1*v to the right, we get:<BR>\n" );
document.write( "  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2Au+=+13+-+1%2Av ALIGN=MIDDLE  ALT=\"1%2Au+=+13+-+1%2Av\"   DISABLED_style= \"max-width:90%; height:auto;\" >, or <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=u+=+13%2F1+-+1%2Av%2F1 ALIGN=MIDDLE  ALT=\"u+=+13%2F1+-+1%2Av%2F1\"   DISABLED_style= \"max-width:90%; height:auto;\" >. Substitute that<BR>\n" );
document.write( "  into another equation:<BR>\n" );
document.write( "  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2A%2813%2F1+-+1%2Av%2F1%29+%2B+-1%5Cv+=+3 ALIGN=MIDDLE  ALT=\"1%2A%2813%2F1+-+1%2Av%2F1%29+%2B+-1%5Cv+=+3\"   DISABLED_style= \"max-width:90%; height:auto;\" > and simplify: So, we know that v=5. Since <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=u+=+13%2F1+-+1%2Av%2F1 ALIGN=MIDDLE  ALT=\"u+=+13%2F1+-+1%2Av%2F1\"   DISABLED_style= \"max-width:90%; height:auto;\" >, u=8.<BR>\n" );
document.write( "  <BR>\n" );
document.write( "  Answer: <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=system%28+u=8%2C+v=5+%29 ALIGN=MIDDLE  ALT=\"system%28+u=8%2C+v=5+%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >.<BR>\n" );
document.write( "  </TD></TR>\n" );
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document.write( " </SPAN>\n" );
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