document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=923611>Question 923611</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I need help solving this problem. \r<BR>\n" );
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document.write( "A paddle boat can move at a speed of 4km/h in still water. The boat is paddled 14km downstream in a river in the same time it takes to go 7km upstream. What is the speed of the river? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #560150 by </B><A HREF=/tutors/aboutme.mpl?userid=rothauserc><B>rothauserc(4718)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=rothauserc><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=rothauserc><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=560150\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> we have two formulas here using rate*time = distance, let x be speed of the river and t be time<BR>\n" );
document.write( "(4+x)*t = 14<BR>\n" );
document.write( "(4-x)*t = 7<BR>\n" );
document.write( "from these two equations we have two expressions for t<BR>\n" );
document.write( "t = 14 / (4+x)<BR>\n" );
document.write( "t = 7 / (4-x)<BR>\n" );
document.write( "set the two expressions equal to each other and solve for x<BR>\n" );
document.write( "14 / (4+x) = 7 / (4-x)<BR>\n" );
document.write( "cross multiply the fractions<BR>\n" );
document.write( "14*(4-x) = 7 * (4+x)<BR>\n" );
document.write( "divide both sides of = by 7<BR>\n" );
document.write( "2*(4-x) = (4+x)<BR>\n" );
document.write( "8-2x = 4+x<BR>\n" );
document.write( "3x = 4<BR>\n" );
document.write( "x = 4/3 = 1.33 km/h<BR>\n" );
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