document.write( "Question 174118: I need your help! Problem 1. Elimination method. Type an integer or a decimal
\n" ); document.write( " 0.05x+0.25y=66
\n" ); document.write( " 0.15x+0.05y=72\r
\n" ); document.write( "\n" ); document.write( "On this problem I keep coming up with(x, y) = (3, 5,-0.5) and each time the answer is wrong. What am I doing wrong?\r
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\n" ); document.write( "\n" ); document.write( "2. Soybean meal is 18% protein: cornmeal is 9% protein. How many pounds of each should be mixed together in order to get 360-ld mixture that is 17% protein.\r
\n" ); document.write( "\n" ); document.write( " Pounds of cornmeal that should be in mixture?\r
\n" ); document.write( "\n" ); document.write( " Pounds of soybean meal should be in mixture? \n" ); document.write( "

Algebra.Com's Answer #129014 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
$\".05x+%2B+.25y+=+66\"$
\n" ); document.write( " $\".15x+%2B+.05y+=+72\"$
\n" ); document.write( "What I would do is multiply both equations by
\n" ); document.write( " $\"100\"$ to get rid of all decimals
\n" ); document.write( "(1) $\"5x+%2B+25y+=+6600\"$
\n" ); document.write( "(2) $\"15x+%2B+5y+=+7200\"$
\n" ); document.write( "Now multiply (2) by $\"5\"$ and subtract (1) from it
\n" ); document.write( "(2) $\"75x+%2B+25y+=+36000\"$
\n" ); document.write( "(1) $\"5x+%2B+25y+=+6600\"$
\n" ); document.write( "(3) $\"70x+=+29400\"$
\n" ); document.write( " $\"x+=+420\"$
\n" ); document.write( "Substitute this into ((1) or (2)
\n" ); document.write( "(1) $\"5x+%2B+25y+=+6600\"$
\n" ); document.write( " $\"5%2A420+%2B+25y+=+6600\"$
\n" ); document.write( " $\"2100+%2B+25y+=+6600\"$
\n" ); document.write( " $\"25y+=+4500\"$
\n" ); document.write( " $\"y+=+180\"$
\n" ); document.write( "The answer is $\"x+=+420\"$ and $\"y+=+180\"$
\n" ); document.write( "check:
\n" ); document.write( "(2) $\"15x+%2B+5y+=+7200\"$
\n" ); document.write( " $\"15%2A420+%2B+5%2A180+=+7200\"$
\n" ); document.write( " $\"6300+%2B+900+=+7200\"$
\n" ); document.write( " $\"7200+=+7200\"$
\n" ); document.write( "OK
\n" ); document.write( "---------------------------
\n" ); document.write( "Let $\"c\"$ = pounds of cornmeal reeded
\n" ); document.write( "Let $\"s\"$ = pounds of soybeans needed
\n" ); document.write( "Given is
\n" ); document.write( " $\"c+%2B+s+=+360\"$ lbs
\n" ); document.write( "In words:
\n" ); document.write( "(pounds of protein from soybeans) + (pounds of protein from cornmeal)
\n" ); document.write( "divided by (total pounds of mixture) = % protein in mixture
\n" ); document.write( " $\"%28.18s+%2B+.09c%29+%2F+360+=+.17\"$
\n" ); document.write( "multiply both sides by $\"360\"$
\n" ); document.write( " $\".18s+%2B+.09c+=+61.2\"$
\n" ); document.write( "Multiply both sides by $\"100\"$
\n" ); document.write( "(1) $\"18s+%2B+9c+=+6120\"$ and, given is
\n" ); document.write( "(2) $\"s+%2B+c+=+360\"$
\n" ); document.write( "Multiply (2) by $\"18\"$ and subtract (1) from (2)
\n" ); document.write( "(1) $\"18s+%2B+9c+=+6120\"$
\n" ); document.write( "(2) $\"18s+%2B+18c+=+6480\"$
\n" ); document.write( "(3) $\"9c+=+360\"$
\n" ); document.write( " $\"c+=+40\"$ and,since
\n" ); document.write( " $\"s+%2B+c+=+360\"$
\n" ); document.write( " $\"s+%2B+40+=+360\"$
\n" ); document.write( " $\"s+=+320\"$
\n" ); document.write( "40 pounds of cornmeal and 320 pound of soybeans are needed
\n" ); document.write( "check:
\n" ); document.write( "(1) $\"18s+%2B+9c+=+6120\"$
\n" ); document.write( " $\"18%2A320+%2B+9%2A40+=+6120\"$
\n" ); document.write( " $\"5760+%2B+360+=+6120\"$
\n" ); document.write( " $\"6120+=+6120\"$
\n" ); document.write( "OK
\n" ); document.write( " \r
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