document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1049079>Question 1049079</A>: <I><SPAN STYLE=\"word-break: break-all;\"> In his&#8203; motorboat, Bill Ruhberg travels upstream at top speed to his favorite fishing&#8203; spot, a distance of 528<BR>\n" );
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document.write( "&#8203;mi, in 6<BR>\n" );
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document.write( "hr.&#8203; Returning, he finds that the trip&#8203; downstream, still at top&#8203; speed, takes only 5.5<BR>\n" );
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document.write( "hr. Find the rate of&#8203; Bill's boat and the speed of the current. Let x&#8203; = the rate of the boat in still water and y&#8203; = 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 #664706 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=664706\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> the required equations are \r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=528%2F6 ALIGN=MIDDLE  ALT=\"528%2F6\"   DISABLED_style= \"max-width:90%; height:auto;\" >=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=u-v ALIGN=MIDDLE  ALT=\"u-v\"   DISABLED_style= \"max-width:90%; height:auto;\" > for upstream<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=528%2F5.5 ALIGN=MIDDLE  ALT=\"528%2F5.5\"   DISABLED_style= \"max-width:90%; height:auto;\" >=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=u%2Bv ALIGN=MIDDLE  ALT=\"u%2Bv\"   DISABLED_style= \"max-width:90%; height:auto;\" > for downstream\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=88 ALIGN=MIDDLE  ALT=\"88\"   DISABLED_style= \"max-width:90%; height:auto;\" >=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=u-v ALIGN=MIDDLE  ALT=\"u-v\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=96 ALIGN=MIDDLE  ALT=\"96\"   DISABLED_style= \"max-width:90%; height:auto;\" >=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=u%2Bv ALIGN=MIDDLE  ALT=\"u%2Bv\"   DISABLED_style= \"max-width:90%; height:auto;\" >\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+=+88%2C%0D%0A++++1%5Cu+%2B+1%5Cv+=+96+%29%0D%0A++ ALIGN=MIDDLE  ALT=\"+system%28+%0D%0A++++1%5Cu+%2B+-1%5Cv+=+88%2C%0D%0A++++1%5Cu+%2B+1%5Cv+=+96+%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+=+88+-+-1%2Av ALIGN=MIDDLE  ALT=\"1%2Au+=+88+-+-1%2Av\"   DISABLED_style= \"max-width:90%; height:auto;\" >, or <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=u+=+88%2F1+-+-1%2Av%2F1 ALIGN=MIDDLE  ALT=\"u+=+88%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%2888%2F1+-+-1%2Av%2F1%29+%2B+1%5Cv+=+96 ALIGN=MIDDLE  ALT=\"1%2A%2888%2F1+-+-1%2Av%2F1%29+%2B+1%5Cv+=+96\"   DISABLED_style= \"max-width:90%; height:auto;\" > and simplify: So, we know that v=4. Since <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=u+=+88%2F1+-+-1%2Av%2F1 ALIGN=MIDDLE  ALT=\"u+=+88%2F1+-+-1%2Av%2F1\"   DISABLED_style= \"max-width:90%; height:auto;\" >, u=92.<BR>\n" );
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document.write( "  Answer: <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=system%28+u=92%2C+v=4+%29 ALIGN=MIDDLE  ALT=\"system%28+u=92%2C+v=4+%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >.<BR>\n" );
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