document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1066350>Question 1066350</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A boat traveled downstream a distance of 50 mi and then came right back. If the speed of the current was 20 mph and the total trip took 3 hours and 20 minutes, find the average speed of the boat relative to the water. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #681523 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=681523\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 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 with no current in mi/hr<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+%2B+20+ ALIGN=MIDDLE  ALT=\"+s+%2B+20+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = the speed of the boat going downstream in mi/hr<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+-+20+ ALIGN=MIDDLE  ALT=\"+s+-+20+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = the speed of the boat going upstream in miles/hr<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 to go downstream<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+10%2F3+-+t+ ALIGN=MIDDLE  ALT=\"+10%2F3+-+t+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = time in hrs to go upstream<BR>\n" );
document.write( "-----------------------------------------<BR>\n" );
document.write( "Going downstream:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+50+=+%28+s+%2B+20+%29%2At+ ALIGN=MIDDLE  ALT=\"+50+=+%28+s+%2B+20+%29%2At+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Going upstream:<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+50+=+%28+s+-+20+%29%2A%28+10%2F3+-+t+%29+ ALIGN=MIDDLE  ALT=\"+50+=+%28+s+-+20+%29%2A%28+10%2F3+-+t+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "-----------------------------------<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+50+=+%2810%2F3%29%2As+-+200%2F3+-+s%2At+%2B+20t+ ALIGN=MIDDLE  ALT=\"+50+=+%2810%2F3%29%2As+-+200%2F3+-+s%2At+%2B+20t+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+150+=+10s+-+200+-+3s%2At+%2B+60t+ ALIGN=MIDDLE  ALT=\"+150+=+10s+-+200+-+3s%2At+%2B+60t+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "and<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+50%2F%28+s%2B20+%29+ ALIGN=MIDDLE  ALT=\"+t+=+50%2F%28+s%2B20+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Plug (1) into (2)<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+150+=+10s+-+200+-+3s%2At+%2B+60t+ ALIGN=MIDDLE  ALT=\"+150+=+10s+-+200+-+3s%2At+%2B+60t+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+150+=+10s+-+200+%2B+t%2A%28+60+-+3s+%29+ ALIGN=MIDDLE  ALT=\"+150+=+10s+-+200+%2B+t%2A%28+60+-+3s+%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=+150+=+10s+-+200+%2B+%28+50%2F%28+s%2B20+%29%29%2A%28+60+-+3s+%29+ ALIGN=MIDDLE  ALT=\"+150+=+10s+-+200+%2B+%28+50%2F%28+s%2B20+%29%29%2A%28+60+-+3s+%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=+350+=+10s+%2B+%28+50%2F%28+s%2B20+%29%29%2A%28+60+-+3s+%29+ ALIGN=MIDDLE  ALT=\"+350+=+10s+%2B+%28+50%2F%28+s%2B20+%29%29%2A%28+60+-+3s+%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=+350%2A%28+s%2B20+%29+=+10s%2A%28+s%2B20+%29+%2B+50%2A%28+60+-+3s+%29+ ALIGN=MIDDLE  ALT=\"+350%2A%28+s%2B20+%29+=+10s%2A%28+s%2B20+%29+%2B+50%2A%28+60+-+3s+%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=+350s+%2B+7000+=+10s%5E2+%2B+200s+%2B+3000+-+150s+ ALIGN=MIDDLE  ALT=\"+350s+%2B+7000+=+10s%5E2+%2B+200s+%2B+3000+-+150s+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+10s%5E2+-+300s+-+4000+=+0+ ALIGN=MIDDLE  ALT=\"+10s%5E2+-+300s+-+4000+=+0+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s%5E2+-+30s+-+400+=+0+ ALIGN=MIDDLE  ALT=\"+s%5E2+-+30s+-+400+=+0+\"   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+-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+=+1+ ALIGN=MIDDLE  ALT=\"+a+=+1+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+b+=+-30+ ALIGN=MIDDLE  ALT=\"+b+=+-30+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+c+=+-400+ ALIGN=MIDDLE  ALT=\"+c+=+-400+\"   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+-%28-30%29+%2B-+sqrt%28+%28-30%29%5E2-4%2A1%2A%28-400%29+%29%29%2F%282%2A1%29+ ALIGN=MIDDLE  ALT=\"+s+=+%28+-%28-30%29+%2B-+sqrt%28+%28-30%29%5E2-4%2A1%2A%28-400%29+%29%29%2F%282%2A1%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+30+%2B-+sqrt%28+900+%2B+1600+%29%29%2F2+ ALIGN=MIDDLE  ALT=\"+s+=+%28+30+%2B-+sqrt%28+900+%2B+1600+%29%29%2F2+\"   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+30+%2B-+sqrt%28+2500+%29+%29%2F2+ ALIGN=MIDDLE  ALT=\"+s+=+%28+30+%2B-+sqrt%28+2500+%29+%29%2F2+\"   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+30+%2B+50+%29+%2F+2+ ALIGN=MIDDLE  ALT=\"+s+=+%28+30+%2B+50+%29+%2F+2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+80%2F2+ ALIGN=MIDDLE  ALT=\"+s+=+80%2F2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+40+ ALIGN=MIDDLE  ALT=\"+s+=+40+\"   DISABLED_style= \"max-width:90%; height:auto;\" > ( can't use the negative solution )<BR>\n" );
document.write( "--------------------<BR>\n" );
document.write( "The speed of the boat with no current is 40 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=+50+=+%28+s+%2B+20+%29%2At+ ALIGN=MIDDLE  ALT=\"+50+=+%28+s+%2B+20+%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=+50+=+%28+40+%2B+20+%29%2At+ ALIGN=MIDDLE  ALT=\"+50+=+%28+40+%2B+20+%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=+50+=+60t+ ALIGN=MIDDLE  ALT=\"+50+=+60t+\"   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+=+5%2F6+ ALIGN=MIDDLE  ALT=\"+t+=+5%2F6+\"   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=+50+=+%28+s+-+20+%29%2A%28+10%2F3+-+t+%29+ ALIGN=MIDDLE  ALT=\"+50+=+%28+s+-+20+%29%2A%28+10%2F3+-+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=+50+=+%28+40+-+20+%29%2A%28+10%2F3+-+t+%29+ ALIGN=MIDDLE  ALT=\"+50+=+%28+40+-+20+%29%2A%28+10%2F3+-+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=+50+=+20%2A%28+10%2F3+-+t+%29+ ALIGN=MIDDLE  ALT=\"+50+=+20%2A%28+10%2F3+-+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=+50+=+200%2F3+-+20t+ ALIGN=MIDDLE  ALT=\"+50+=+200%2F3+-+20t+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+150+=+200+-+60t+ ALIGN=MIDDLE  ALT=\"+150+=+200+-+60t+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+60t+=+50+ ALIGN=MIDDLE  ALT=\"+60t+=+50+\"   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+=+5%2F6+ ALIGN=MIDDLE  ALT=\"+t+=+5%2F6+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "OK\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );