document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=570085>Question 570085</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I do not understand how to work these problems, I am pretty good at algebra but i do not understand what formula to use or how to work through them, any help is appreciated.\r<BR>\n" );
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document.write( "The radiator in a certain make of car needs to contain 70 liters of 40% antifreeze. the radiator now contains 70 liters of 20% antifreeze. How many liters of this solvent must be drained and replaced with  00% antifreeze to get the desired strength?  <BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #367571 by </B><A HREF=/tutors/aboutme.mpl?userid=KMST><B>KMST(5328)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=KMST><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=KMST><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=367571\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> If the radiator has 20% antifreeze now and it needs 40%, you may need to replace some of the liquid with 100% antifreeze (not 00%, which I think is some kind of typo).<BR>\n" );
document.write( "This kind of problem requires that you do some accounting of both, the total volume, and the amount of the substance of interest that is mixed in.<BR>\n" );
document.write( "The total volume you need is 70 L.<BR>\n" );
document.write( "The total amount of antifreeze that you need in those 70 L is<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=0.4%2A70 ALIGN=MIDDLE  ALT=\"0.4%2A70\"   DISABLED_style= \"max-width:90%; height:auto;\" > L = 28 L<BR>\n" );
document.write( "If you remove <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x ALIGN=MIDDLE  ALT=\"x\"   DISABLED_style= \"max-width:90%; height:auto;\" > L of what is in the radiator now, and replace them with <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x ALIGN=MIDDLE  ALT=\"x\"   DISABLED_style= \"max-width:90%; height:auto;\" > L of 100% antifreeze, you expect to have 70 L again in the end.<BR>\n" );
document.write( "The final amount of antifreeze in there will be<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=0.2%2870-x%29 ALIGN=MIDDLE  ALT=\"0.2%2870-x%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > L from the <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=70-x ALIGN=MIDDLE  ALT=\"70-x\"   DISABLED_style= \"max-width:90%; height:auto;\" > L of 20% antifreeze solution not removed, plus<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x ALIGN=MIDDLE  ALT=\"x\"   DISABLED_style= \"max-width:90%; height:auto;\" > L that were added, so the total (as a function of <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x ALIGN=MIDDLE  ALT=\"x\"   DISABLED_style= \"max-width:90%; height:auto;\" > ) is<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=0.2%2870-x%29%2Bx=14-0.2x%2Bx=14%2B0.8x ALIGN=MIDDLE  ALT=\"0.2%2870-x%29%2Bx=14-0.2x%2Bx=14%2B0.8x\"   DISABLED_style= \"max-width:90%; height:auto;\" > L<BR>\n" );
document.write( "So we need to find the <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x ALIGN=MIDDLE  ALT=\"x\"   DISABLED_style= \"max-width:90%; height:auto;\" > that will make that the needed 28 L of antifreeze calculated above.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=0.8x%2B14=28 ALIGN=MIDDLE  ALT=\"0.8x%2B14=28\"   DISABLED_style= \"max-width:90%; height:auto;\" > --> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=0.8x=14 ALIGN=MIDDLE  ALT=\"0.8x=14\"   DISABLED_style= \"max-width:90%; height:auto;\" > --> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x=14%2F0.8 ALIGN=MIDDLE  ALT=\"x=14%2F0.8\"   DISABLED_style= \"max-width:90%; height:auto;\" > --> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=highlight%28x=17.5%29 ALIGN=MIDDLE  ALT=\"highlight%28x=17.5%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > L </SPAN>\n" );
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