document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=176000>Question 176000</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A motorboat travels 147km in 3 hours going upstream and 546km in 6 hours going downstream. What is the speed of the boat in still water, and what is the speed of the current? <BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #131154 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=131154\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A motorboat travels 147km in 3 hours going upstream and 546km in 6 hours going downstream. What is the speed of the boat in still water, and what is the speed of the current?<BR>\n" );
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document.write( "Let x = boat speed in still water<BR>\n" );
document.write( "Let y = speed of the current<BR>\n" );
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document.write( "Write two distance equations, one for upstream and one for downstream<BR>\n" );
document.write( "dist = time * speed<BR>\n" );
document.write( "3x - 3y = 147<BR>\n" );
document.write( "and<BR>\n" );
document.write( "6x + 6y = 546<BR>\n" );
document.write( "simplify, divide equation by 2<BR>\n" );
document.write( "3x + 3y = 273<BR>\n" );
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document.write( "Add these two equations<BR>\n" );
document.write( "3x - 3y = 147<BR>\n" );
document.write( "3x + 3y = 273<BR>\n" );
document.write( "-----------------addition eliminates y, find x<BR>\n" );
document.write( "6x = 420<BR>\n" );
document.write( "x = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=420%2F6 ALIGN=MIDDLE  ALT=\"420%2F6\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "x = 70 km/hr in still water<BR>\n" );
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document.write( "Find the current using the upstream equation<BR>\n" );
document.write( "3(70) - 3y = 147<BR>\n" );
document.write( "210 - 3y = 147<BR>\n" );
document.write( "-3y = 147 + 210<BR>\n" );
document.write( "-3y = -63<BR>\n" );
document.write( "y = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28-63%29%2F%28-3%29 ALIGN=MIDDLE  ALT=\"%28-63%29%2F%28-3%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "y = +21 km/hr is the current<BR>\n" );
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document.write( "Check solution in the down stream equation<BR>\n" );
document.write( "6(70 + 21) = <BR>\n" );
document.write( "6 * 91 = 546, confirms our solutions\r<BR>\n" );
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