document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1058973>Question 1058973</A>: <I><SPAN STYLE=\"word-break: break-all;\"> An airplane travels 300 km from Manila and back in 4 hours and 30 minutes. The wind speed is 10 kph, what is the speed of the plane in still air? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #674048 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=674048\">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 plane in km/hr in still air<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+%2B+10+ ALIGN=MIDDLE  ALT=\"+s+%2B+10+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = the speed of the plane flying with the wind<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+-+10+ ALIGN=MIDDLE  ALT=\"+s+-+10+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = the speed of the plane flying against the wind<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 flying with the wind<BR>\n" );
document.write( "The one-way distance is <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+300%2F2+=+150+ ALIGN=MIDDLE  ALT=\"+300%2F2+=+150+\"   DISABLED_style= \"max-width:90%; height:auto;\" > km<BR>\n" );
document.write( "-------------------------------------------<BR>\n" );
document.write( "Equation for flying with the wind:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+150+=+%28+s+%2B+10+%29%2At+ ALIGN=MIDDLE  ALT=\"+150+=+%28+s+%2B+10+%29%2At+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Equation for flying against the wind:<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+150+=+%28+s+-+10+%29%2A%28+4.5+-+t+%29+ ALIGN=MIDDLE  ALT=\"+150+=+%28+s+-+10+%29%2A%28+4.5+-+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+=+150%2F%28+s+%2B+10+%29+ ALIGN=MIDDLE  ALT=\"+t+=+150%2F%28+s+%2B+10+%29+\"   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=+150+=+4.5s+-+45+-+s%2At+%2B+10t+ ALIGN=MIDDLE  ALT=\"+150+=+4.5s+-+45+-+s%2At+%2B+10t+\"   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+%2B+45+=+4.5s+-+t%2A%28+s+-+10+%29+ ALIGN=MIDDLE  ALT=\"+150+%2B+45+=+4.5s+-+t%2A%28+s+-+10+%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+%2B+45+=+4.5s+-+%28+150%2F%28+s%2B10+%29+%29%2A%28+s+-+10+%29+ ALIGN=MIDDLE  ALT=\"+150+%2B+45+=+4.5s+-+%28+150%2F%28+s%2B10+%29+%29%2A%28+s+-+10+%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=+195+=+4.5s+-%28+150s+%2F+%28+s%2B10+%29+-+1500%2F%28+s+%2B+10+%29%29+%7D%7D%7C%7D%0D%0A%282%29+%7B%7B%7B+195+=+4.5s+-+150s+%2F+%28+s%2B10+%29+%2B+1500%2F%28+s+%2B+10+%29+%7D%7D%7C%7D%0D%0AMultiply+both+sides+by+%7B%7B%7B+s+%2B+10+ ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+195%2A%28+s%2B+10+%29+=+4.5s%2A%28+s+%2B+10+%29+-+150s+%2B+1500+ ALIGN=MIDDLE  ALT=\"+195%2A%28+s%2B+10+%29+=+4.5s%2A%28+s+%2B+10+%29+-+150s+%2B+1500+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+195s+%2B+1950+=+4.5s%5E2+%2B+45s+-+150s+%2B+1500+ ALIGN=MIDDLE  ALT=\"+195s+%2B+1950+=+4.5s%5E2+%2B+45s+-+150s+%2B+1500+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4.5s%5E2+-+195s+%2B+45s+-+150s+%2B+1500+-+1950+=+0+ ALIGN=MIDDLE  ALT=\"+4.5s%5E2+-+195s+%2B+45s+-+150s+%2B+1500+-+1950+=+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=+4.5s%5E2+-300s+-+450+=+0+ ALIGN=MIDDLE  ALT=\"+4.5s%5E2+-300s+-+450+=+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=+45s%5E2+-+3000s+-+4500+=+0+ ALIGN=MIDDLE  ALT=\"+45s%5E2+-+3000s+-+4500+=+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=+9s%5E2+-+600s+-+900+=+0+ ALIGN=MIDDLE  ALT=\"+9s%5E2+-+600s+-+900+=+0+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "--------------------------------<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+=+9+ ALIGN=MIDDLE  ALT=\"+a+=+9+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+b+=+-600+ ALIGN=MIDDLE  ALT=\"+b+=+-600+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+c+=+-900+ ALIGN=MIDDLE  ALT=\"+c+=+-900+\"   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-%28-600%29+%2B-+sqrt%28+%28-600%29%5E2+-+4%2A9%2A%28-900%29+%29%29+%2F+%282%2A9%29+ ALIGN=MIDDLE  ALT=\"+s+=+%28-%28-600%29+%2B-+sqrt%28+%28-600%29%5E2+-+4%2A9%2A%28-900%29+%29%29+%2F+%282%2A9%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+600+%2B-+sqrt%28+360000+%2B+32400+%29%29+%2F+18+ ALIGN=MIDDLE  ALT=\"+s+=+%28+600+%2B-+sqrt%28+360000+%2B+32400+%29%29+%2F+18+\"   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+600+%2B-+sqrt%28+392400+%29++%29+%2F+18+ ALIGN=MIDDLE  ALT=\"+s+=+%28+600+%2B-+sqrt%28+392400+%29++%29+%2F+18+\"   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+600+%2B+626.418+%29+%2F+18+ ALIGN=MIDDLE  ALT=\"+s+=+%28+600+%2B+626.418+%29+%2F+18+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+1226.418%2F18+ ALIGN=MIDDLE  ALT=\"+s+=+1226.418%2F18+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+s+=+68.134+ ALIGN=MIDDLE  ALT=\"+s+=+68.134+\"   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
document.write( "----------------<BR>\n" );
document.write( "The speed of the plane in still air is 68.134 km/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=+150+=+%28+s+%2B+10+%29%2At+ ALIGN=MIDDLE  ALT=\"+150+=+%28+s+%2B+10+%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=+150+=+%28+68.134+%2B+10+%29%2At ALIGN=MIDDLE  ALT=\"+150+=+%28+68.134+%2B+10+%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=+t+=+150+%2F+78.134+ ALIGN=MIDDLE  ALT=\"+t+=+150+%2F+78.134+\"   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+=+1.92+ ALIGN=MIDDLE  ALT=\"+t+=+1.92+\"   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=+150+=+%28+s+-+10+%29%2A%28+4.5+-+t+%29+ ALIGN=MIDDLE  ALT=\"+150+=+%28+s+-+10+%29%2A%28+4.5+-+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=+150+=+%28+68.134+-+10+%29%2A%28+4.5+-+t+%29+ ALIGN=MIDDLE  ALT=\"+150+=+%28+68.134+-+10+%29%2A%28+4.5+-+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=+150+%2F+58.134+=+4.5+-+t+ ALIGN=MIDDLE  ALT=\"+150+%2F+58.134+=+4.5+-+t+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+2.5802+=+4.5+-+t+ ALIGN=MIDDLE  ALT=\"+2.5802+=+4.5+-+t+\"   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+=+4.5+-+2.5802+ ALIGN=MIDDLE  ALT=\"+t+=+4.5+-+2.5802+\"   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+=+1.92+ ALIGN=MIDDLE  ALT=\"+t+=+1.92+\"   DISABLED_style= \"max-width:90%; height:auto;\" > hrs<BR>\n" );
document.write( "OK<BR>\n" );
document.write( "Pretty strange numbers -ususally they<BR>\n" );
document.write( "come out simple decimals. You might<BR>\n" );
document.write( "want a 2nd opinion, too.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );