document.write( "Question 1129217: \"The radiator in your car contains 4 gallons of antifreeze and water. The mixture is 45% antifreeze. How much of the mixture should be drained and replaced with pure antifreeze in order to have a 60% antifreeze solution? Solve as a system of linear equations in two variables and round to the nearest tenth of a gallon.\" \n" ); document.write( "
Algebra.Com's Answer #745779 by josmiceli(19441)\"\" \"About 
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Let \"+a+\" = gallons of pure antifreeze drained from radiator
\n" ); document.write( "Let \"+b+\" = total gallons of mixture removed from radiator
\n" ); document.write( "------------------------
\n" ); document.write( "(1) \"+a+=+.45b+\"
\n" ); document.write( "(2) \"+%28+-a+%2B+b+%29+%2F+4+=+.6+\"
\n" ); document.write( "----------------------------------
\n" ); document.write( "(2) \"+-a+%2B+b+=+2.4+\"
\n" ); document.write( "(2) \"+-.45b+%2B+b+=+2.4+\"
\n" ); document.write( "(2) \"+.55b+=+2.4+\"
\n" ); document.write( "(2) \"+b+=+4.364+\"
\n" ); document.write( "4.4 gallons of mixture should be removed
\n" ); document.write( "-------------------
\n" ); document.write( "check:
\n" ); document.write( "\"+a+=+.45%2A4.364+\"
\n" ); document.write( "\"+a+=+1.964+\"
\n" ); document.write( "\"+%28+-1.964+%2B+4.364+%29%2F4+=+.6+\"
\n" ); document.write( "\"+2.4002+=+2.4+\"
\n" ); document.write( "error due to rounding off
\n" ); document.write( "OK\r
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