document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=823236>Question 823236</A>: <I><SPAN STYLE=\"word-break: break-all;\"> How in the world do you set this guy up?\r<BR>\n" );
document.write( "\n" );
document.write( "A boat travels 25 miles per hour in still water. It takes 3 and 1/3 hours in total for the boat to travel 40 miles up a river and then return by the same route. What is the speed of the current in the river?\r<BR>\n" );
document.write( "\n" );
document.write( "Think you guys could help me set it up?\r<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #495339 by </B><A HREF=/tutors/aboutme.mpl?userid=TimothyLamb><B>TimothyLamb(4379)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=TimothyLamb><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=TimothyLamb><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=495339\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> ---<BR>\n" );
document.write( "s = d / t<BR>\n" );
document.write( "t = d / s<BR>\n" );
document.write( "T = 40/(25 - w) + 40/(25 + w)<BR>\n" );
document.write( "T = 40(25 + w)/(25 - w)(25 + w) + 40(25 - w)/(25 - w)(25 + w)<BR>\n" );
document.write( "T(25 - w)(25 + w) = 40(25 + w) + 40(25 - w)<BR>\n" );
document.write( "T(625 - ww) = 1000 + 40w + 1000 - 40w<BR>\n" );
document.write( "T(625 - ww) = 2000<BR>\n" );
document.write( "625 - ww = 2000/T<BR>\n" );
document.write( "T = 3+1/3 = 10/3<BR>\n" );
document.write( "625 - ww = 2000/(10/3)<BR>\n" );
document.write( "-ww + 625 = 600<BR>\n" );
document.write( "-ww + 25 = 0<BR>\n" );
document.write( "---<BR>\n" );
document.write( "the above quadratic equation is in standard form, with a=-1, b=0, and c=25<BR>\n" );
document.write( "---<BR>\n" );
document.write( "to solve the quadratic equation, by using the quadratic formula, copy and paste this:<BR>\n" );
document.write( "-1 0 25<BR>\n" );
document.write( "into this solver: https://sooeet.com/math/quadratic-equation-solver.php<BR>\n" );
document.write( "---<BR>\n" );
document.write( "this quadratic has two real roots (the x-intercepts), which are:<BR>\n" );
document.write( "w = -5<BR>\n" );
document.write( "w = 5<BR>\n" );
document.write( "---<BR>\n" );
document.write( "negative speed doesn't make sense for this problem, so use the positive root<BR>\n" );
document.write( "---<BR>\n" );
document.write( "answer:<BR>\n" );
document.write( "the speed of the current in the river is 5 mph<BR>\n" );
document.write( "---<BR>\n" );
document.write( "Solve and graph linear equations:<BR>\n" );
document.write( "https://sooeet.com/math/linear-equation-solver.php<BR>\n" );
document.write( "---<BR>\n" );
document.write( "Solve quadratic equations, quadratic formula:<BR>\n" );
document.write( "https://sooeet.com/math/quadratic-formula-solver.php<BR>\n" );
document.write( "---<BR>\n" );
document.write( "Solve systems of linear equations up to 6-equations 6-variables:<BR>\n" );
document.write( "https://sooeet.com/math/system-of-linear-equations-solver.php </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );