document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1147215>Question 1147215</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Can you please help me find the formula for this question?<BR>\n" );
document.write( "A jet left Singapore five hours before a passenger plane. The planes flew in opposite directions. The passenger plane flew 315 mph for four hours. After this time the planes were 5670 miles apart. What was the jet's speed? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #768522 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><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=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=768522\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> rate * time = distance.\r<BR>\n" );
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document.write( "the passenger plan flew 315 miles per hour for 4 hours.<BR>\n" );
document.write( "that means it traveled 315 * 4 = 1260 miles.\r<BR>\n" );
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document.write( "the jet flew 5 more hours for a total of 9 hours and flew 5670 - 1260 = 4410 miles.\r<BR>\n" );
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document.write( "the jets's speed was 4410 / 9 = 490 miles per hour.\r<BR>\n" );
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document.write( "your formulas would be:\r<BR>\n" );
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document.write( "r * t = d<BR>\n" );
document.write( "let r1 and t1 and d1 be the formula for the passenger plane.<BR>\n" );
document.write( "let r2 and t2 and d2 be the formula for the jet.\r<BR>\n" );
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document.write( "since they were going in opposite directions, their distance traveled was additive.\r<BR>\n" );
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document.write( "you get d1 + d2 = 5670.<BR>\n" );
document.write( "since r1 * t1 = d1 and r2 * t2 = d2, then you get:<BR>\n" );
document.write( "r1 * t1 + r2 * t2 = 5670\r<BR>\n" );
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document.write( "since the passenger plane flew 315 miles per hour in 4 hours, then r1 = 315 and t1 = 4 and the formula for the passsenger plane becomes 315 * 4 = d1<BR>\n" );
document.write( "solve for d1 to get d1 = 4 * 315 = 1260 and the formula for the passenber plane becomes 315 * 4 = 1260\r<BR>\n" );
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document.write( "since the jet left 5 hours before the passenger plane, then t2 = t1 + 5<BR>\n" );
document.write( "since t1 = 4, then t2 = 4 + 5 = 9.\r<BR>\n" );
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document.write( "since d1 + d2 = 5670, and since d2 = 1260, then d1 = 5670 - 1260 = 4410.\r<BR>\n" );
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document.write( "you get t1 = 9 and d1 = 4410 and the formula becomes r1 * 9 = 4410.<BR>\n" );
document.write( "solve for r1 to get r1 = 4410 / 9 = 490.\r<BR>\n" );
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document.write( "the formula for the jet becomes 490 * 9 = 4410<BR>\n" );
document.write( "the formula for the passenger plane becomes 315 * 4 = 1260<BR>\n" );
document.write( "d1 + d2 = 5670<BR>\n" );
document.write( "r1 * t1 + r2 * t2 becomes 490 * 9 + 315 * 4 = 5670.\r<BR>\n" );
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document.write( "either way you slice it, the answer is the same.<BR>\n" );
document.write( "the jet's speed is 490 miles per hour.\r<BR>\n" );
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document.write( "the formula that helped to answer this question is rate * time = distance.<BR>\n" );
document.write( "the rest was mostly logic.\r<BR>\n" );
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document.write( " </SPAN>\n" );
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