document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=707663>Question 707663</A>: <I><SPAN STYLE=\"word-break: break-all;\"> please explain the step for this I have no idea.<BR>\n" );
document.write( "the speed of the current in a river is 6 mph a ferry operator who works that part of the river is looking to buy a new boat for his business everyday his route takes him 22.5 miles against the current and back to his deck and he needs this trip in a total of 9 hours he has a boat in mind but he can only test it on a lake where there in no current how fast must the boat go on the lake in order for it to serve the ferry operators needs </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #435812 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=435812\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> the speed of the current in a river is 6 mph a ferry operator who works that part of the river is looking to buy a new boat for his business everyday his route takes him 22.5 miles against the current and back to his deck and he needs this trip in a total of 9 hours he has a boat in mind but he can only test it on a lake where there in no current how fast must the boat go on the lake in order for it to serve the ferry operators needs<BR>\n" );
document.write( "----<BR>\n" );
document.write( "Solve for boat speed in still water.<BR>\n" );
document.write( "---<BR>\n" );
document.write( "Against current DATA:<BR>\n" );
document.write( "distance = 22.5 miles ; rate = b-6 mph ; time = d/r = 22.5/(b-6) hrs.<BR>\n" );
document.write( "-----<BR>\n" );
document.write( "With current DATA:<BR>\n" );
document.write( "distance = 22.5 miles ; rate = b+6 mph ; time = d/r = 22.5/(b+6) hrs<BR>\n" );
document.write( "----<BR>\n" );
document.write( "Equation:<BR>\n" );
document.write( "time + time = 9 hrs<BR>\n" );
document.write( "22.5/(b-6) + 22.5/(b+6) = 9 hrs<BR>\n" );
document.write( "------<BR>\n" );
document.write( "22.5(b+6) + 22.5(b-6) = 9(b^2-36)<BR>\n" );
document.write( "45b = 9(b^2-36)<BR>\n" );
document.write( "5b = b^2-36<BR>\n" );
document.write( "b^2-5b-36 = 0<BR>\n" );
document.write( "Factor:<BR>\n" );
document.write( "b^2-9b+4b-36 = 0<BR>\n" );
document.write( "b(b-9)+4(b-9) = 0<BR>\n" );
document.write( "(b-9)(b+4) = 0<BR>\n" );
document.write( "----<BR>\n" );
document.write( "Positive solution:<BR>\n" );
document.write( "b = 9 mph (required speed of the boat in still water)<BR>\n" );
document.write( "=================<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
document.write( "====================<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );