document.write( "Question 146587: Soybean meal is 16% protein; cornmela is 8% protein. How many pounds of each should be mixed together in order to get 320-lb mixture that is 14% protein?\r
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Algebra.Com's Answer #107036 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
let x= # of pounds of soybean meal and y=# of pounds of cornmeal \r
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\n" ); document.write( "\n" ); document.write( "Since we want a 320 mixture, this means that we have the first equation: \r
\n" ); document.write( "\n" ); document.write( "\"x%2By=320\"\r
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\n" ); document.write( "\n" ); document.write( "Also, because we want a \"320-lb mixture that is 14% protein\" from the mixture of
\n" ); document.write( "soybean meal that is 16% protein and \"cornmeal that is 8% protein, we have the second equation:\r
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\n" ); document.write( "\n" ); document.write( "\"0.16x%2B0.08y=320%280.14%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"0.16x%2B0.08y=44.8\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "\"10%280.16x%2B0.08y%29=10%2844.8%29\" Multiply both sides by 10 to remove the decimals\r
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\n" ); document.write( "\n" ); document.write( "\"16x%2B8y=4480\" Distribute \r
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\n" ); document.write( "\n" ); document.write( "So we have the new system of equations:\r
\n" ); document.write( "\n" ); document.write( "\"system%28x%2By=320%2C16x%2B8y=4480%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x%2By=320\" Start with the first equation\r
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\n" ); document.write( "\n" ); document.write( "\"y=320-x\" Subtract \"x\" from both sides\r
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\n" ); document.write( "\n" ); document.write( "\"y=-x%2B320\" Rearrange the equation\r
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\n" ); document.write( "\n" ); document.write( "Since \"y=-x%2B320\", we can now replace each \"y\" in the second equation with \"-x%2B320\" to solve for \"x\"\r
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\n" ); document.write( "\n" ); document.write( "\"16x%2B8highlight%28%28-x%2B320%29%29=4480\" Plug in \"y=-x%2B320\" into the first equation. In other words, replace each \"y\" with \"-x%2B320\". Notice we've eliminated the \"y\" variables. So we now have a simple equation with one unknown.\r
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\n" ); document.write( "\n" ); document.write( "\"16x%2B%288%29%28-1%29x%2B%288%29%28320%29=4480\" Distribute \"8\" to \"-x%2B320\"\r
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\n" ); document.write( "\n" ); document.write( "\"16x-8x%2B2560=4480\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "\"8x%2B2560=4480\" Combine like terms on the left side\r
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\n" ); document.write( "\n" ); document.write( "\"8x=4480-2560\"Subtract 2560 from both sides\r
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\n" ); document.write( "\n" ); document.write( "\"8x=1920\" Combine like terms on the right side\r
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\n" ); document.write( "\n" ); document.write( "\"x=%281920%29%2F%288%29\" Divide both sides by 8 to isolate x\r
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\n" ); document.write( "\n" ); document.write( "\"x=240\" Divide\r
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\n" ); document.write( "\n" ); document.write( "-----------------First Answer------------------------------\r
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\n" ); document.write( "\n" ); document.write( "So the first part of our answer is: \"x=240\"\r
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\n" ); document.write( "\n" ); document.write( "Since we know that \"x=240\" we can plug it into the equation \"y=-x%2B320\" (remember we previously solved for \"y\" in the first equation).\r
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\n" ); document.write( "\n" ); document.write( "\"y=-x%2B320\" Start with the equation where \"y\" was previously isolated.\r
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\n" ); document.write( "\n" ); document.write( "\"y=-%28240%29%2B320\" Plug in \"x=240\"\r
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\n" ); document.write( "\n" ); document.write( "\"y=-240%2B320\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "\"y=80\" Combine like terms \r
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\n" ); document.write( "\n" ); document.write( "-----------------Second Answer------------------------------\r
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\n" ); document.write( "\n" ); document.write( "So the second part of our answer is: \"y=80\"\r
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\n" ); document.write( "\n" ); document.write( "-----------------Summary------------------------------\r
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\n" ); document.write( "\n" ); document.write( "So our answers are:\r
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\n" ); document.write( "\n" ); document.write( "\"x=240\" and \"y=80\"\r
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\n" ); document.write( "\n" ); document.write( "which form the ordered pair \r
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\n" ); document.write( "\n" ); document.write( "So there are 240 pounds of Soybean meal and 80 pounds of cornmeal\r
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