document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=809730>Question 809730</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A 20% acid solution is mixed with a 70% acid solution to get 50 liters of a 40% solution.\r<BR>\n" );
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document.write( "How much of the 70% solution is used?\r<BR>\n" );
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document.write( "and \r<BR>\n" );
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document.write( "Going against the current, a boat takes 6 hours to make a 120-mile trip. When the boat travels with the current on the return trip, it takes 5 hours.\r<BR>\n" );
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document.write( "If x = the rate of the boat in still water and y = the rate of the current, which of the following systems could be used to solve the problem?\r<BR>\n" );
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document.write( "a.) 6(x - y) = 120 and 5(x + y) = 120<BR>\n" );
document.write( "b.) 6(x + y) = 120 and 5(x - y) = 120<BR>\n" );
document.write( "c.) 6x - 5y = 120 and x + y = 120 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #487744 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=487744\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+a+ ALIGN=MIDDLE  ALT=\"+a+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = liters of 20% solution needed<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+b+ ALIGN=MIDDLE  ALT=\"+b+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = liters of 70% solution needed<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+a+%2B+b+=+50+ ALIGN=MIDDLE  ALT=\"+a+%2B+b+=+50+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+%28+.2a+%2B+.7b+%29+%2F+50+=+.4+ ALIGN=MIDDLE  ALT=\"+%28+.2a+%2B+.7b+%29+%2F+50+=+.4+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "--------------------------<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+.2a+%2B+.7b+=+.4%2A50+ ALIGN=MIDDLE  ALT=\"+.2a+%2B+.7b+=+.4%2A50+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+.2a+%2B+.7b+=+20+ ALIGN=MIDDLE  ALT=\"+.2a+%2B+.7b+=+20+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+2a+%2B+7b+=+200+ ALIGN=MIDDLE  ALT=\"+2a+%2B+7b+=+200+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Multiply both sides of (1) by <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2 ALIGN=MIDDLE  ALT=\"2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "and subtract (1) from (2)<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+2a+%2B+7b+=+200+ ALIGN=MIDDLE  ALT=\"+2a+%2B+7b+=+200+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+-2a+-2b+=+-100+ ALIGN=MIDDLE  ALT=\"+-2a+-2b+=+-100+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+5b+=+100+ ALIGN=MIDDLE  ALT=\"+5b+=+100+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+b+=+20+ ALIGN=MIDDLE  ALT=\"+b+=+20+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "and, since<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+a+%2B+b+=+50+ ALIGN=MIDDLE  ALT=\"+a+%2B+b+=+50+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+a+=+30+ ALIGN=MIDDLE  ALT=\"+a+=+30+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "30 liters of 20% solution are needed<BR>\n" );
document.write( "20 liters of 70% solution are needed<BR>\n" );
document.write( "check:<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+%28+.2%2A30+%2B+.7%2A20+%29+%2F+50+=+.4+ ALIGN=MIDDLE  ALT=\"+%28+.2%2A30+%2B+.7%2A20+%29+%2F+50+=+.4+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+%28+6+%2B+14+%29+%2F+50+=+.4+ ALIGN=MIDDLE  ALT=\"+%28+6+%2B+14+%29+%2F+50+=+.4+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+20+=+.4%2A50+ ALIGN=MIDDLE  ALT=\"+20+=+.4%2A50+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+20+=+20+ ALIGN=MIDDLE  ALT=\"+20+=+20+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "OK<BR>\n" );
document.write( "----------------------------<BR>\n" );
document.write( "(a) is the answer<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+d+=+r%2At+ ALIGN=MIDDLE  ALT=\"+d+=+r%2At+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Subtract the rate of the current from the rate of the boat<BR>\n" );
document.write( "in still water when going against the current<BR>\n" );
document.write( "---------<BR>\n" );
document.write( "Add the 2 rates when going with the current<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );