document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1193696>Question 1193696</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Nate flies a plane against a headwind for 3869 miles. The return trip with the wind took 20 hours less time. If the wind speed is 10 mph, how fast does Nate fly the plane when there is no wind? </SPAN>\n" );
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document.write( "Let x be the plane speed (mph).<br><BR>\n" );
document.write( "Then its speed with the wind is x+10, and its speed against the wind is x-10.<br><BR>\n" );
document.write( "The time for flying 3869 miles with the wind is 3869/(x+10); the time for flying 3869 miles against the wind is 3869/(x-10).<br><BR>\n" );
document.write( "The time for flying with the wind was 20 hours less than the time for flying against the wind:<br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=3869%2F%28x-10%29-3869%2F%28x%2B10%29=20 ALIGN=MIDDLE  ALT=\"3869%2F%28x-10%29-3869%2F%28x%2B10%29=20\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "Multiply everything by the common denominator:<br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=3869%28x%2B10%29-3869%28x-10%29=20%28x%2B10%29%28x-10%29 ALIGN=MIDDLE  ALT=\"3869%28x%2B10%29-3869%28x-10%29=20%28x%2B10%29%28x-10%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=3869x%2B38690-3869x%2B38690=20%28x%5E2-100%29 ALIGN=MIDDLE  ALT=\"3869x%2B38690-3869x%2B38690=20%28x%5E2-100%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=77380=20x%5E2-2000 ALIGN=MIDDLE  ALT=\"77380=20x%5E2-2000\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=79380=20x%5E2 ALIGN=MIDDLE  ALT=\"79380=20x%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x%5E2=3969 ALIGN=MIDDLE  ALT=\"x%5E2=3969\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x=63 ALIGN=MIDDLE  ALT=\"x=63\"   DISABLED_style= \"max-width:90%; height:auto;\" ><br><BR>\n" );
document.write( "ANSWER: The speed of the plane in still air is x = 63mph<br><BR>\n" );
document.write( " </SPAN>\n" );
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