document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=681941>Question 681941</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I need help with Linear systems word problems. Onf question that I am having trouble with is:<BR>\n" );
document.write( "One plane at 520 feet is ascending at a rate of 40 feet per minute, while another plane at 3800 feet is desending at a rate of 120 feet per minute. How long will it take the two planes to be at the same altitude? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #422862 by </B><A HREF=/tutors/aboutme.mpl?userid=Alan3354><B>Alan3354(69443)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Alan3354><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=Alan3354><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=422862\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> One plane at 520 feet is ascending at a rate of 40 feet per minute, while another plane at 3800 feet is desending at a rate of 120 feet per minute. How long will it take the two planes to be at the same altitude?<BR>\n" );
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document.write( "h(t) = 520 - 40t = 3800 - 120t<BR>\n" );
document.write( "520 - 40t = 3800 - 120t<BR>\n" );
document.write( "80t = 3280<BR>\n" );
document.write( "t = 41 minutes<BR>\n" );
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document.write( "but,<BR>\n" );
document.write( "the first plane will hit the ground in 13 minutes, the 2nd will impact at 31.67 minutes.<BR>\n" );
document.write( "So they'll be at the same altitude, zero, at 31.67 minutes.<BR>\n" );
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