document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=784848>Question 784848</A>: <I><SPAN STYLE=\"word-break: break-all;\"> please help me solve:\r<BR>\n" );
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document.write( "Kevin drove 320 miles to a resort.  He return trip took 20 min longer because his speed returning was 4 mi/h slower than going </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #477294 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=477294\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Kevin drove 320 miles to a resort.<BR>\n" );
document.write( " He return trip took 20 min longer because his speed returning was 4 mi/h slower than going<BR>\n" );
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document.write( "Let (s+4) = speed of the outbound trip<BR>\n" );
document.write( "then<BR>\n" );
document.write( "s = speed of the return trip<BR>\n" );
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document.write( "Change 20 min to 1/3 hr<BR>\n" );
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document.write( "Write a time equation; time = dist/speed<BR>\n" );
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document.write( "return time - outbound time = 20 min<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=320%2Fs ALIGN=MIDDLE  ALT=\"320%2Fs\"   DISABLED_style= \"max-width:90%; height:auto;\" > - <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=320%2F%28%28s%2B4%29%29 ALIGN=MIDDLE  ALT=\"320%2F%28%28s%2B4%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F3 ALIGN=MIDDLE  ALT=\"1%2F3\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "multiply by 3s(s+4) to clear the denominators, resulting in:\<BR>\n" );
document.write( "3(s+4)(320) - 3s(320) = s(s+4)<BR>\n" );
document.write( "960s + 3840 - 960s = s^2 + 4s<BR>\n" );
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document.write( "Arrange as a quadratic equation on the right<BR>\n" );
document.write( "0 = s^2 + 4s - 3840<BR>\n" );
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document.write( "You can use the quadratic formula here but this will factor to<BR>\n" );
document.write( "(s+64)(s-60) = 0<BR>\n" );
document.write( "the positive solution<BR>\n" );
document.write( "s = 60 mph on the return trip<BR>\n" );
document.write( "and obviously 64 mph on the outbound trip<BR>\n" );
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document.write( "Confirm this by finding the actual times<BR>\n" );
document.write( "320/60 = 5.33<BR>\n" );
document.write( "320/64 = 5.00<BR>\n" );
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document.write( "dif: .33 hrs which is 20 min\r<BR>\n" );
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