document.write( "Question 145889: 1. An animal feed is made from three ingredients: corn, soybeans, and cottonseed. One unit of each ingredient provides units of protein, fat, and fiber, as shown below:\r
\n" ); document.write( "\n" ); document.write( "Each unit of corn provides .25 units of protein, .4 units of fat, and .3 units of fiber.
\n" ); document.write( "Each unit of soybeans provides .4 units of protein, .2 units of fat, and .2 units of fiber.
\n" ); document.write( "Each unit of cottonseed provides .2 units of protein, .3 units of fat, and .1 units of fiber.\r
\n" ); document.write( "\n" ); document.write( "How many units of each ingredient should be used to make a feed that contains 22 units of protein, 28 units of fat, and 18 units of fiber?
\n" ); document.write( " \n" ); document.write( "
Algebra.Com's Answer #106494 by ankor@dixie-net.com(22740)\"\" \"About 
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An animal feed is made from three ingredients: corn, soybeans, and cottonseed. One unit of each ingredient provides units of protein, fat, and fiber, as shown below:
\n" ); document.write( "Each unit of corn provides .25 units of protein, .4 units of fat, and .3 units of fiber.
\n" ); document.write( "Each unit of soybeans provides .4 units of protein, .2 units of fat, and .2 units of fiber.
\n" ); document.write( "Each unit of cottonseed provides .2 units of protein, .3 units of fat, and .1 units of fiber.
\n" ); document.write( "How many units of each ingredient should be used to make a feed that contains 22 units of protein, 28 units of fat, and 18 units of fiber?
\n" ); document.write( ":
\n" ); document.write( "Let x, y, z = amt of corn, soybeans, cottonseed respectively
\n" ); document.write( ":
\n" ); document.write( "Three equations:
\n" ); document.write( "pro: .25x + .40y + .20z = 22
\n" ); document.write( "fat: .40x + .20y + .30z = 28
\n" ); document.write( "fib: .30x + .20y + .10z = 18
\n" ); document.write( ":
\n" ); document.write( "Multiply the 1st equation by -1 and add the 3 equations.
\n" ); document.write( "-.25x - .40y - .20z = -22
\n" ); document.write( "+.40x + .20y + .30z = 28
\n" ); document.write( "+.30x + .20y + .10z = 18
\n" ); document.write( "-------------------------
\n" ); document.write( "+.45x + 0y + .20z = 24
\n" ); document.write( ":
\n" ); document.write( "Multiply the 3rd equation by -1 and add to the 2nd equation
\n" ); document.write( "+.40x + .20y + .30z = 28
\n" ); document.write( "-.30x - .20y - .10z = -18
\n" ); document.write( "--------------------------
\n" ); document.write( "+.10x + 0y + .20z = +10
\n" ); document.write( ":
\n" ); document.write( "Two equation where we are dealing only with x and z
\n" ); document.write( ".45x + .20z = 24
\n" ); document.write( ".10x + .20z = 10
\n" ); document.write( "------------------subtracting eliminates z, find x:
\n" ); document.write( ".35x = 14
\n" ); document.write( "x = \"14%2F.35\"
\n" ); document.write( "x = 40 units of corn
\n" ); document.write( ":
\n" ); document.write( "Use equation: .10x + .20z = 10; substitute 40 for x:
\n" ); document.write( ".10(40) + .20z = 10
\n" ); document.write( "4 + .2z = 10
\n" ); document.write( ".2z = 10 - 4
\n" ); document.write( "z = \"6%2F.2\"
\n" ); document.write( "z = 30 units of cottonseed
\n" ); document.write( ":
\n" ); document.write( "I'll let you find y \n" ); document.write( "
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