document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=421890>Question 421890</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A messenger takes a total of 9 hours of driving from a warehouse to a store and back to the warehouse by the same route. On the trip to the store the messenger average 28 kph and returning to the warehouse he averages 35 kph. How long did it take the messenger to get to the store? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #294893 by </B><A HREF=/tutors/aboutme.mpl?userid=htmentor><B>htmentor(1343)</B></A><img src=\"/images/stars/stars-12.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=htmentor><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=htmentor><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=294893\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let t1 = time from warehouse to store<BR>\n" );
document.write( "Let t2 = time from store to warehouse<BR>\n" );
document.write( "The total time = t = t1 + t2<BR>\n" );
document.write( "We are given v1 = 28 kph, v2 = 35 kph<BR>\n" );
document.write( "Since the distance, d, to and from the warehouse is the same, we have:<BR>\n" );
document.write( "d = v1*t1 and d = v2*t2<BR>\n" );
document.write( "Setting the RHS of the two equations equal to one another, we have:<BR>\n" );
document.write( "v1*t1 = v2*t2<BR>\n" );
document.write( "We want to solve for t1, so we set t2 = t - t1 -> t1 = (v2/v1)*(t-t1)<BR>\n" );
document.write( "Solving for t1 gives (v1/v2)*t1 + t1 = t -> t1*(1+(v1/v2) = t -> t1 = t/(1+v1/v2)<BR>\n" );
document.write( "So the travel time to the store = 9 hr/(1+28/35) = 5 hr.<BR>\n" );
document.write( " </SPAN>\n" );
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