document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=147410>Question 147410</A>: <I><SPAN STYLE=\"word-break: break-all;\"> An airplane flew for 3 hours with a tail wind of 40 km/hr.  The return flight against the same wind took 4 hours. Find the speed of the airplane 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 #107831 by </B><A HREF=/tutors/aboutme.mpl?userid=Electrified_Levi><B>Electrified_Levi(103)</B></A><img src=\"/images/stars/stars-09.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Electrified_Levi><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=107831\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Hi , Hope I can help<BR>\n" );
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document.write( "An airplane flew for 3 hours with a tail wind of 40 km/hr.  The return flight against the same wind took 4 hours. Find the speed of the airplane in still air.<BR>\n" );
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document.write( "The airplane flew the same amount of miles each way.<BR>\n" );
document.write( "Distance= (Rate)(Time)<BR>\n" );
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document.write( "We know the Time for each way, 3 hours with the wind, and 4 hours against the wind<BR>\n" );
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document.write( "We know that \"x\" is how fast it is going in still air.<BR>\n" );
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document.write( "Since the wind is adding to the speed on the first trip, we know that the speed is equal to (x+40)<BR>\n" );
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document.write( "On the return trip the plane is going against the wind, and decreasing the speed of the airplane, so the speed is equal to (x-40)<BR>\n" );
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document.write( "Now that we know both the time and the rate, we can solve it.<BR>\n" );
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document.write( "Distance = (Rate)(Time), or<BR>\n" );
document.write( "(Rate)(Time)=(Rate)(Time)<BR>\n" );
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document.write( "Now we can put numbers in<BR>\n" );
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document.write( "(x + 40)(3) = (x - 40)(4)<BR>\n" );
document.write( "3(x + 40) = 4(x - 40)<BR>\n" );
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document.write( "We will use distribution property,<BR>\n" );
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document.write( "3x + 120 = 4x - 160<BR>\n" );
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document.write( "We will now subtract 3x from both sides<BR>\n" );
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document.write( "0 + 120 = x - 160<BR>\n" );
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document.write( "We will add 160 to both sides<BR>\n" );
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document.write( "160 + 120 = x + 0<BR>\n" );
document.write( "x = 280<BR>\n" );
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document.write( "The airplane is going 280 km/hr. in still air.<BR>\n" );
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document.write( "You can check by replacing \"x\" with \"280\"<BR>\n" );
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document.write( "3(x + 40) = 4(x - 40)<BR>\n" );
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document.write( "3(280 + 40) = 4(280 - 40)<BR>\n" );
document.write( "3(320) = 4(240)<BR>\n" );
document.write( "(960 = 960)<BR>\n" );
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document.write( "The airplane also went 960 miles, each way.<BR>\n" );
document.write( "1,920 miles all together.<BR>\n" );
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document.write( "Hope I helped, Levi </SPAN>\n" );
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