document.write( "Question 1176875: A farmer has several packages of fertilizer for his new grain crop. The old packages contain 60 pounds of long-term growth supplement and 50 pounds of weed killer. The new packages contain 45 pounds of long-term growth supplement and 65 pounds of weed killer. Using past experiences, the farmer estimates that he needs 1350 pounds of long-term growth supplement and 1400 pounds of weed killer for the fields. How many old packages of fertilizer and how many new packages of fertilizer should he use? \n" ); document.write( "
Algebra.Com's Answer #804861 by Theo(13342)\"\" \"About 
You can put this solution on YOUR website!
let x = the number of old packages and y = the number of new packages.\r
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\n" ); document.write( "\n" ); document.write( "create a table as shown below:\r
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document.write( "                                          x                y\r\n" );
document.write( "description                              old              new         total\r\n" );
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document.write( "long term growth supplements              60               45          1350\r\n" );
document.write( "weed killer                               50               65          1400\r\n" );
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\n" ); document.write( "\n" ); document.write( "the two equations that need to be solved simultaneously are:\r
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\n" ); document.write( "\n" ); document.write( "60x + 45y = 1350
\n" ); document.write( "50x + 65y = 1400\r
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\n" ); document.write( "\n" ); document.write( "multiply both sides of the first equation by 5 and both sides of the second equation by 6 to get:\r
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\n" ); document.write( "\n" ); document.write( "300x + 225y = 6750
\n" ); document.write( "300x + 390y = 8400\r
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\n" ); document.write( "\n" ); document.write( "subtract the first equation from the second to get:\r
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\n" ); document.write( "\n" ); document.write( "165y = 1650\r
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\n" ); document.write( "\n" ); document.write( "solve for y to get:\r
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\n" ); document.write( "\n" ); document.write( "y = 1650 / 165 = 10\r
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\n" ); document.write( "\n" ); document.write( "solve for x in the first equation to get:\r
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\n" ); document.write( "\n" ); document.write( "300x + 225 * 10 = 6750
\n" ); document.write( "solve for x to get:
\n" ); document.write( "x = (6750 - 2250) / 300 = 4500 / 300 = 15\r
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\n" ); document.write( "\n" ); document.write( "you have x = 15 and y = 10\r
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\n" ); document.write( "\n" ); document.write( "go back to the original equations and replace x and y with these values to get:\r
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\n" ); document.write( "\n" ); document.write( "60x + 45y = 1350 becomes 60 * 15 + 45 * 10 = 1350 which becomes 900 + 450 = 1350 which becomes 1350 = 1350 which is true.\r
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\n" ); document.write( "\n" ); document.write( "50x + 65y = 1400 becomes 50 * 15 + 65 * 10 = 1400 which becomes 750 + 650 = 1400 which becomes 1400 = 1400 which is true.\r
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\n" ); document.write( "\n" ); document.write( "the values of x and y are confirmed to be good.\r
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\n" ); document.write( "\n" ); document.write( "your solution is that he should use 15 old packages and 10 new packages.\r
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