document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=761700>Question 761700</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Before I begin I thank you so much for your time!! it means a lot to me and you are helping me out of a jam.  The problem: Tonya's outboard can drive her boat at 7mph in still water.  it takes her 10 minutes more to reach her friends camp 4 miles up the river than to return to her camp down river.  What is the speed of the current?\r<BR>\n" );
document.write( "\n" );
document.write( "I set up two different equations, one for coming and one for going. t=time c=current speed<BR>\n" );
document.write( "(1)going: 4=(7-c)*(t+10)<BR>\n" );
document.write( "(2)returning: 4=(7+c)*t<BR>\n" );
document.write( "I rearranged equation (2) to equal: {4/(7+c)}=t<BR>\n" );
document.write( "I then plugged this into The first equation to create this: 4=(7-c)*{4/(7+c)+10}<BR>\n" );
document.write( "This is where I start getting confused... I dont know how to get the (7+c) out of the denominator. Do I multiply everything by (7+c)? Or just the 4? OR should I not even get it out of the denominator and just multiply everything out? Thanks again! -Abby </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #463424 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=463424\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Tonya's outboard can drive her boat at 7mph in still water. it takes her 10 minutes more to reach her friends camp 4 miles up the river than to return to her camp down river. What is the speed of the current?<BR>\n" );
document.write( "------<BR>\n" );
document.write( "Upstream DATA:<BR>\n" );
document.write( "distance = 4 miles ; rate = 7-c mph ; time = d/r = 4/(7-c) hrs<BR>\n" );
document.write( "--------------------------------------<BR>\n" );
document.write( "Downstream DATA:<BR>\n" );
document.write( "distance = 4 miles ; rate = 7+c mph ; time = d/r = 4/(7+c) hrs<BR>\n" );
document.write( "------<BR>\n" );
document.write( "Equation:<BR>\n" );
document.write( "down time - up time = 1/6 hr<BR>\n" );
document.write( "----<BR>\n" );
document.write( "4/(7+c) - 4/(7-c) = 1/6<BR>\n" );
document.write( "-----<BR>\n" );
document.write( "24(7-c) - 24(7+c) = 7^2-c^2<BR>\n" );
document.write( "----<BR>\n" );
document.write( "-48c = 49 - c^2<BR>\n" );
document.write( "------<BR>\n" );
document.write( "c^2 - 48c - 49 = 0<BR>\n" );
document.write( "------<BR>\n" );
document.write( "(c-49)(c+1) = 0\r<BR>\n" );
document.write( "\n" );
document.write( "----<BR>\n" );
document.write( "Usable answer: c = 49<BR>\n" );
document.write( "===================================<BR>\n" );
document.write( "Note: that answer doesn't make much sense if the boat's speed<BR>\n" );
document.write( "in still water is only 7 mph.<BR>\n" );
document.write( "===================================<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
document.write( "================== </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );