document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1157547>Question 1157547</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The current of a river is 2 miles per hour. It takes a motorboat a total of 3 hours to travel 8 miles upstream and return 8 miles downstream. What is the speed of the boat in still water? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #780422 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=780422\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+c+=+2+ ALIGN=MIDDLE  ALT=\"+c+=+2+\"   DISABLED_style= \"max-width:90%; height:auto;\" > mi/hr is the speed of the current<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+ ALIGN=MIDDLE  ALT=\"+s+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = the speed of the boat in still water<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 the upstream trip<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+3+-+t+ ALIGN=MIDDLE  ALT=\"+3+-+t+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = time in hrs for the downstream trip<BR>\n" );
document.write( "-------------------------------------------------------<BR>\n" );
document.write( "Equation for going upstream:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+8+=+%28+s+-+c+%29%2At+ ALIGN=MIDDLE  ALT=\"+8+=+%28+s+-+c+%29%2At+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "equation for going downstream:<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+8+=+%28+s+%2B+c+%29%2A%28+3+-+t+%29+ ALIGN=MIDDLE  ALT=\"+8+=+%28+s+%2B+c+%29%2A%28+3+-+t+%29+\"   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=+8+=+%28+s+-+2+%29%2At+ ALIGN=MIDDLE  ALT=\"+8+=+%28+s+-+2+%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=+8+=+%28+s+%2B+2+%29%2A%28+3+-+t+%29+ ALIGN=MIDDLE  ALT=\"+8+=+%28+s+%2B+2+%29%2A%28+3+-+t+%29+\"   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+=+8%2F+%28+s+-+2+%29+ ALIGN=MIDDLE  ALT=\"+t+=+8%2F+%28+s+-+2+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Plug this into (2)<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+8+=+%28+s+%2B+2+%29%2A%28+3+-+8%2F%28+s-2+%29%29+ ALIGN=MIDDLE  ALT=\"+8+=+%28+s+%2B+2+%29%2A%28+3+-+8%2F%28+s-2+%29%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=+8+=+3s+%2B+6+-+%28+8s+%29+%2F+%28+s-2+%29+-+16+%2F+%28+s-2+%29+ ALIGN=MIDDLE  ALT=\"+8+=+3s+%2B+6+-+%28+8s+%29+%2F+%28+s-2+%29+-+16+%2F+%28+s-2+%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=+2+=+3s+-+%28+8s+-+16+%29+%2F+%28+s-2+%29+ ALIGN=MIDDLE  ALT=\"+2+=+3s+-+%28+8s+-+16+%29+%2F+%28+s-2+%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=+s+-+2+ ALIGN=MIDDLE  ALT=\"+s+-+2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+2%2A%28+s+-+2+%29+=+3s%2A%28+s-2+%29+-+8s+-+16+ ALIGN=MIDDLE  ALT=\"+2%2A%28+s+-+2+%29+=+3s%2A%28+s-2+%29+-+8s+-+16+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+2s+-+4+=+3s%5E2+-+6s+-+8s+-+16+ ALIGN=MIDDLE  ALT=\"+2s+-+4+=+3s%5E2+-+6s+-+8s+-+16+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+3s%5E2+-+16s+-+12+=+0+ ALIGN=MIDDLE  ALT=\"+3s%5E2+-+16s+-+12+=+0+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Use quadratic formula<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+%28+-b+%2B-+sqrt%28+b%5E2+-+4%2Aa%2Ac+%29%29%2F%282%2Aa%29+ ALIGN=MIDDLE  ALT=\"+s+=+%28+-b+%2B-+sqrt%28+b%5E2+-+4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+a+=+3+ ALIGN=MIDDLE  ALT=\"+a+=+3+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+b+=+-16+ ALIGN=MIDDLE  ALT=\"+b+=+-16+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+c+=+-12+ ALIGN=MIDDLE  ALT=\"+c+=+-12+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+%28+-%28-16%29+%2B-+sqrt%28+%28-16%29%5E2+-+4%2A3%2A%28-12%29+%29%29%2F%282%2A3%29+ ALIGN=MIDDLE  ALT=\"+s+=+%28+-%28-16%29+%2B-+sqrt%28+%28-16%29%5E2+-+4%2A3%2A%28-12%29+%29%29%2F%282%2A3%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+%28+16+%2B-+sqrt%28+256+%2B+144+%29%29+%2F+6+ ALIGN=MIDDLE  ALT=\"+s+=+%28+16+%2B-+sqrt%28+256+%2B+144+%29%29+%2F+6+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+%28+16+%2B-+sqrt%28+400+%29%29+%2F+6+ ALIGN=MIDDLE  ALT=\"+s+=+%28+16+%2B-+sqrt%28+400+%29%29+%2F+6+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+%28+16+%2B+20+%29+%2F+6+ ALIGN=MIDDLE  ALT=\"+s+=+%28+16+%2B+20+%29+%2F+6+\"   DISABLED_style= \"max-width:90%; height:auto;\" > ( can't use the negative solution )<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+6+ ALIGN=MIDDLE  ALT=\"+s+=+6+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The speed of the boat in still water is 6 mi/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=+8+=+%28+s+-+c+%29%2At+ ALIGN=MIDDLE  ALT=\"+8+=+%28+s+-+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=+8+=+%28+6+-+2+%29%2At+ ALIGN=MIDDLE  ALT=\"+8+=+%28+6+-+2+%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=+8+=+4t+ ALIGN=MIDDLE  ALT=\"+8+=+4t+\"   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+=+2+ ALIGN=MIDDLE  ALT=\"+t+=+2+\"   DISABLED_style= \"max-width:90%; height:auto;\" > hrs<BR>\n" );
document.write( "and<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+8+=+%28+s+%2B+c+%29%2A%28+3+-+t+%29+ ALIGN=MIDDLE  ALT=\"+8+=+%28+s+%2B+c+%29%2A%28+3+-+t+%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=+8+=+%28+6+%2B+2+%29%2A%28+3+-+t+%29+ ALIGN=MIDDLE  ALT=\"+8+=+%28+6+%2B+2+%29%2A%28+3+-+t+%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=+8+=+8%2A%28+3+-+t+%29+ ALIGN=MIDDLE  ALT=\"+8+=+8%2A%28+3+-+t+%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=+8+=+24+-+8t+ ALIGN=MIDDLE  ALT=\"+8+=+24+-+8t+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+8t+=+16+ ALIGN=MIDDLE  ALT=\"+8t+=+16+\"   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+=+2+ ALIGN=MIDDLE  ALT=\"+t+=+2+\"   DISABLED_style= \"max-width:90%; height:auto;\" > hrs<BR>\n" );
document.write( "OK<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );