document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=447136>Question 447136</A>: <I><SPAN STYLE=\"word-break: break-all;\"> \"C leaves from home going 40 kilometers per hour (km/h). When C is 9 km from home, D starts after C from the same place, going 58 km/h. How long does it take for D to catch up with C?\"\r<BR>\n" );
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document.write( "I know the formula is \"d=r*t\", but other than that I'm confused. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #307883 by </B><A HREF=/tutors/aboutme.mpl?userid=richard1234><B>richard1234(7193)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=richard1234><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=richard1234><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=307883\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> You could use D = rt on each person, but the faster way is to note the difference in the speeds.\r<BR>\n" );
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document.write( "Since D is going 18 km/h faster than C, then relative to C, D is moving at 18 km/h. They are originally 9 km apart, so\r<BR>\n" );
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document.write( "9 km = (18 km/h)t --> t = 1/2 hr = 30 minutes.\r<BR>\n" );
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document.write( "(Note that when we used relative speeds, we were allowed to assume that C is stationary and D is moving at 18 km/h). </SPAN>\n" );
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