document.write( "Question 1154014: How many gallons of 20% alcohol solution and 45% alcohol solution must be mixed to get 10 gallons of 25% alcohol solution? \n" ); document.write( "
Algebra.Com's Answer #776363 by josmiceli(19441)\"\" \"About 
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Let \"+a+\" = gallons of 20% solution needed
\n" ); document.write( "Let \"+b+\" = gallons of 45% solution needed
\n" ); document.write( "---------------------------------------------------
\n" ); document.write( "(1) \"+a+%2B+b+=+10+\"
\n" ); document.write( "(2) \"+%28+.2a+%2B+.45b+%29+%2F+10+=+.25+\"
\n" ); document.write( "-----------------------------------------
\n" ); document.write( "(2) \"+.2a+%2B+.45b+=+2.5+\"
\n" ); document.write( "(2) \"+20a+%2B+45b+=+250+\"
\n" ); document.write( "(2) \"+4a+%2B+9b+=+50+\"
\n" ); document.write( "Multiply both sides of (1) by \"4\"
\n" ); document.write( "and subtract (1) from (2)
\n" ); document.write( "(2) \"+4a+%2B+9b+=+50+\"
\n" ); document.write( "(1) \"+-4a+-+4b+=+-40+\"
\n" ); document.write( "-----------------------------
\n" ); document.write( "\"+5b+=+10+\"
\n" ); document.write( "\"+b+=+2+\"
\n" ); document.write( "and
\n" ); document.write( "(1) \"+a+%2B+2+=+10+\"
\n" ); document.write( "(1) \"+a+=+8+\"
\n" ); document.write( "---------------------------
\n" ); document.write( "8 gallons of 20% solution are needed
\n" ); document.write( "2 gallons of 45% solution are needed
\n" ); document.write( "--------------------------------------------
\n" ); document.write( "check:
\n" ); document.write( "(2) \"+%28+.2a+%2B+.45b+%29+%2F+10+=+.25+\"
\n" ); document.write( "(2) \"+%28+.2%2A8+%2B+.45%2A2+%29+%2F+10+=+.25+\"
\n" ); document.write( "(2) \"+%28+1.6+%2B+.9+%29+%2F+10+=+.25+\"
\n" ); document.write( "(2) \"+2.5+=+10%2A.25+\"
\n" ); document.write( "(2) \"+2.5+=+2.5+\"
\n" ); document.write( "OK
\n" ); document.write( "
\n" );