document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=653157>Question 653157</A>: <I><SPAN STYLE=\"word-break: break-all;\"> With a  wind velocity of 30 miles per hour, it takes an airplane as long to travel 840 miles with the wind as 660 miles against it. how fast can the airplane travel 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 #408276 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=408276\">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=+p+ ALIGN=MIDDLE  ALT=\"+p+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = speed of plane in still air<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+p+%2B+30+ ALIGN=MIDDLE  ALT=\"+p+%2B+30+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = speed of plane flying with the wind<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+p+-+30+ ALIGN=MIDDLE  ALT=\"+p+-+30+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = speed of 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;\" > = flight time in both directions<BR>\n" );
document.write( "---------------<BR>\n" );
document.write( "Flying with the wind:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+840+=+%28+p+%2B+30+%29%2At+ ALIGN=MIDDLE  ALT=\"+840+=+%28+p+%2B+30+%29%2At+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Flying against the wind:<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+660+=+%28+p+-+30+%29%2At+ ALIGN=MIDDLE  ALT=\"+660+=+%28+p+-+30+%29%2At+\"   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+=+840+%2F+%28+p+%2B+30+%29+ ALIGN=MIDDLE  ALT=\"+t+=+840+%2F+%28+p+%2B+30+%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=+t+=+660+%2F+%28+p+-+30+%29+ ALIGN=MIDDLE  ALT=\"+t+=+660+%2F+%28+p+-+30+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "By substitution:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+840+%2F+%28+p+%2B+30+%29+=+660+%2F+%28+p+-+30+%29+ ALIGN=MIDDLE  ALT=\"+840+%2F+%28+p+%2B+30+%29+=+660+%2F+%28+p+-+30+%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=+%28+p+%2B+30+%29%2A%28+p+-+30+%29+ ALIGN=MIDDLE  ALT=\"+%28+p+%2B+30+%29%2A%28+p+-+30+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+840%2A%28+p+-+30+%29+=+660%2A%28+p+%2B+30+%29+ ALIGN=MIDDLE  ALT=\"+840%2A%28+p+-+30+%29+=+660%2A%28+p+%2B+30+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+840p+-+25200+=+660p+%2B+19800+ ALIGN=MIDDLE  ALT=\"+840p+-+25200+=+660p+%2B+19800+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+180p+=+45000+ ALIGN=MIDDLE  ALT=\"+180p+=+45000+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+p+=+250+ ALIGN=MIDDLE  ALT=\"+p+=+250+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "The speed of the plane in still air is 250 mi/hr<BR>\n" );
document.write( "check:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+t+=+840+%2F+%28+250+%2B+30+%29+ ALIGN=MIDDLE  ALT=\"+t+=+840+%2F+%28+250+%2B+30+%29+\"   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+=+840+%2F+280+ ALIGN=MIDDLE  ALT=\"+t+=+840+%2F+280+\"   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+=+3+ ALIGN=MIDDLE  ALT=\"+t+=+3+\"   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=+t+=+660+%2F+%28+250+-+30+%29+ ALIGN=MIDDLE  ALT=\"+t+=+660+%2F+%28+250+-+30+%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=+t+=+660+%2F+220+ ALIGN=MIDDLE  ALT=\"+t+=+660+%2F+220+\"   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+=+3+ ALIGN=MIDDLE  ALT=\"+t+=+3+\"   DISABLED_style= \"max-width:90%; height:auto;\" > hrs<BR>\n" );
document.write( "OK\r<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );