document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=414498>Question 414498</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A plane flies 720 miles against the wind in 3 hours. The return trip with the wind takes only 2 1/2 hours. Find the speed of the wind. Find the speed of the plane in still air.  Can you show me how to set this problem and how to work it please? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #290749 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=290749\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A plane flies 720 miles against the wind in 3 hours.<BR>\n" );
document.write( " The return trip with the wind takes only 2 1/2 hours.<BR>\n" );
document.write( " Find the speed of the wind.<BR>\n" );
document.write( " Find the speed of the plane in still air<BR>\n" );
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document.write( "Let s = speed of the plane in still air<BR>\n" );
document.write( "Let w = speed of the wind<BR>\n" );
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document.write( "Then we can say<BR>\n" );
document.write( "(s+w) = effective speed with the wind<BR>\n" );
document.write( "and<BR>\n" );
document.write( "(s-w) = effective speed against the wind<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Write a distance equation for each trip; dist = time * speed<BR>\n" );
document.write( "2.5(s+w) = 720<BR>\n" );
document.write( "and<BR>\n" );
document.write( "3(s-w) = 720<BR>\n" );
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document.write( "We can simplify this and use elimination to solve this<BR>\n" );
document.write( "divide the 1st equation by 2.5<BR>\n" );
document.write( "s + w = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=720%2F2.5 ALIGN=MIDDLE  ALT=\"720%2F2.5\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "s + w = 288<BR>\n" );
document.write( "and<BR>\n" );
document.write( "divide the 2nd equation by 3<BR>\n" );
document.write( "s - w = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=720%2F3 ALIGN=MIDDLE  ALT=\"720%2F3\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "s - w = 240<BR>\n" );
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document.write( "Add these two equations.<BR>\n" );
document.write( "s - w = 240<BR>\n" );
document.write( "s + w = 288<BR>\n" );
document.write( "----------------addition eliminates w, find s<BR>\n" );
document.write( "2s = 528<BR>\n" );
document.write( "s = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=528%2F2 ALIGN=MIDDLE  ALT=\"528%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "s = 264 mph is the plane speed in still air<BR>\n" );
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document.write( "Find w using the equation: s + w = 288<BR>\n" );
document.write( "264 + w = 288<BR>\n" );
document.write( "w = 288 - 264<BR>\n" );
document.write( "w = 24 mph is the wind speed<BR>\n" );
document.write( ":<BR>\n" );
document.write( "Check solutions in the 2nd original equation: 3(s-w) = 720<BR>\n" );
document.write( "3(264 - 24) =<BR>\n" );
document.write( "3 * 240 = 720 mi confirms our solutions of s = 264, w = 24<BR>\n" );
document.write( " </SPAN>\n" );
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