document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=59640>Question 59640</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Andy drove his motorboat downstream for 5 hours before heading back. After cruising back upstream for 7 hours, Andy was 10 miles short of his starting point. If the speed of the river is 5 mph, find the speed of his boat in still water? What distance did Andy cruise downstream before heading back? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #40914 by </B><A HREF=/tutors/aboutme.mpl?userid=josmiceli><B>josmiceli(19441)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josmiceli><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=josmiceli><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=40914\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let s = speed in still water<BR>\n" );
document.write( "(5 + s)*5 = (-5 + s)*7 +10<BR>\n" );
document.write( "This equation says that the distance travelled downstream equals <BR>\n" );
document.write( "the distance travelled upstream plus 10 miles (rate*time = rate*time + 10 miles)<BR>\n" );
document.write( "25 + 5s = -35 + 7s + 10<BR>\n" );
document.write( "25 + 35 - 10 = 7s - 5s<BR>\n" );
document.write( "50 = 2s<BR>\n" );
document.write( "s = 25 miles per hour<BR>\n" );
document.write( "The distance travelled downstream is (5 + s)*5<BR>\n" );
document.write( "(5 + 25)*5 = 150 miles<BR>\n" );
document.write( "check to see that this equals the other side of the equation<BR>\n" );
document.write( "150 = (-5 + s)*7 + 10<BR>\n" );
document.write( "150 = (-5 + 25)*7 + 10<BR>\n" );
document.write( "150 = 140 + 10<BR>\n" );
document.write( "150 = 150<BR>\n" );
document.write( "OK </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );