document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=155469>Question 155469</A>: <I><SPAN STYLE=\"word-break: break-all;\"> This is totally confusing to me, how do you set this up and solve this problem?\r<BR>\n" );
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document.write( "Flying agains the jet stream a jet travels 4200 km in 5 hours. flying wih the jetstream, the same jet travels 10620 km in 9 hours.  What is the speed of the jet still in the air, and what is the speed of the jet stream? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #114488 by </B><A HREF=/tutors/aboutme.mpl?userid=nerdybill><B>nerdybill(7384)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=nerdybill><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=nerdybill><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=114488\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> You must apply the distance formula:<BR>\n" );
document.write( "d = rt<BR>\n" );
document.write( "where<BR>\n" );
document.write( "d is distance<BR>\n" );
document.write( "r is rate or speed<BR>\n" );
document.write( "t is time<BR>\n" );
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document.write( "Let x = speed of jet stream<BR>\n" );
document.write( "and y = speed of the jet in still air<BR>\n" );
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document.write( "Since we have two unknowns, we'll need two equations.<BR>\n" );
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document.write( "From:\"Flying against the jet stream a jet travels 4200 km in 5 hours.\" we get equation 1<BR>\n" );
document.write( "5(y-x) = 4200<BR>\n" );
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document.write( "From:\"flying with the jet stream, the same jet travels 10620 km in 9 hours.\" we get equation 2<BR>\n" );
document.write( "9(y+x) = 10620<BR>\n" );
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document.write( "Solve equation 1 for y:<BR>\n" );
document.write( "5(y-x) = 4200<BR>\n" );
document.write( "y-x = 840<BR>\n" );
document.write( "y = 840+x<BR>\n" );
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document.write( "Using the above definition of 'y', substitute it into equation 2 and solve for 'x':<BR>\n" );
document.write( "9(y+x) = 10620<BR>\n" );
document.write( "9(840+x+x) = 10620<BR>\n" );
document.write( "9(840+2x) = 10620<BR>\n" );
document.write( "840+2x = 1180<BR>\n" );
document.write( "2x = 340<BR>\n" );
document.write( "x = 170 mph (speed of jet stream)<BR>\n" );
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document.write( "Using the above definition of 'x', substitute it into equation 1 and solve for y:<BR>\n" );
document.write( "5(y-x) = 4200<BR>\n" );
document.write( "5(y-170) = 4200<BR>\n" );
document.write( "y-170 = 840<BR>\n" );
document.write( "y = 1010 mph (speed of jet in still air) </SPAN>\n" );
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