document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=526663>Question 526663</A>: <I><SPAN STYLE=\"word-break: break-all;\"> How many gallons of 70% antifreeze solution must be mixed with 90 gallons of 25% antifreeze to get a mixture of that is 60% antifreeze? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #348609 by </B><A HREF=/tutors/aboutme.mpl?userid=oberobic><B>oberobic(2304)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=oberobic><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=348609\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> With mixture problems, you need to keep track of how much 'pure' stuff you need.<BR>\n" );
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document.write( "You need to end up a mixture that is 60% antifreeze.<BR>\n" );
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document.write( "You have 90 gallons of 25% antifreeze, which means it has .25*90 = 22.5 gallons of pure antifreeze mixed with a solvent (probably water).<BR>\n" );
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document.write( "You will add 'x' gallons of 70% antifreeze to make the 60% mixture.<BR>\n" );
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document.write( "So, at the conclusion, you will have (90+x) gallons @ 60% 'pure' antifreeze.  That can be shown with the equation:<BR>\n" );
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document.write( ".25*90 + .7*x = .6*(90+x)<BR>\n" );
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document.write( "Multiply by 100 to eliminate fractions.<BR>\n" );
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document.write( "25*90 + 70x = 60(90 +x)<BR>\n" );
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document.write( "2250 + 70x = 5400 + 60x<BR>\n" );
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document.write( "10x = 5400 -2250<BR>\n" );
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document.write( "10x = 3150<BR>\n" );
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document.write( "x = 315 gallons of 70% antifreeze.<BR>\n" );
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document.write( "How much will you end up having on hand?<BR>\n" );
document.write( "90 + 315 = 405 gallons<BR>\n" );
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document.write( "If it is 60% antifreeze, how much 'pure' antifreeze will be in the mixture?<BR>\n" );
document.write( ".6*405 = 243<BR>\n" );
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document.write( "In the original 90 gallons, you have 22.5 gallons of pure antifreeze.<BR>\n" );
document.write( "In the additional 315 gallons, you have .7*315 = 220.5 gallons.<BR>\n" );
document.write( "22.5+220.5 = 243 gallons<BR>\n" );
document.write( "Correct.<BR>\n" );
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document.write( "Answer: Add 315 gallons of 70% antifreeze to 90 gallons of 25% antifreeze to make a 60% mixture.<BR>\n" );
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document.write( "Done. </SPAN>\n" );
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