document.write( "Question 985545: Your younger brother is saving up to buy an ipad. He has a total of 25 coins, all nickels and quarters.The total value is $3.85. How many nickels does he have? How many quarters? Solve by using a system of equations and show all your work. Please help me with this, thank you :) \n" ); document.write( "
Algebra.Com's Answer #606419 by Edwin McCravy(20054)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "Let the number of Nickels be x\r\n" );
document.write( "Let the number of Quarters be y\r\n" );
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document.write( "                      Value      Value\r\n" );
document.write( "Type       Number       of         of\r\n" );
document.write( " of          of        EACH       ALL\r\n" );
document.write( "coin        coins      coin      coins\r\n" );
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document.write( "Nickels       x      $0.05     $0.05x\r\n" );
document.write( "Quarters      y      $0.25     $0.25y\r\n" );
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document.write( "TOTALS       25      -----     $3.85\r\n" );
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document.write( " The first equation comes from the second column.\r\n" );
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document.write( "  \"%28matrix%283%2C1%2CNumber%2Cof%2CNickels%29%29\"\"%22%22%2B%22%22\"\"%28matrix%283%2C1%2CNumber%2Cof%2CQuarters%29%29\"\"%22%22=%22%22\"\"%28matrix%284%2C1%2Ctotal%2Cnumber%2Cof%2Ccoins%29%29\"\r\n" );
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document.write( "             x + y = 25\r\n" );
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document.write( "The second equation comes from the last column:\r\n" );
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document.write( "  \"%28matrix%284%2C1%2CValue%2Cof%2CALL%2CNickels%29%29\"\"%22%22%2B%22%22\"\"%28matrix%284%2C1%2CValue%2Cof%2CALL%2CQuarters%29%29\"\"%22%22=%22%22\"\"%28matrix%285%2C1%2CTotal%2Cvalue%2Cof%2CALL%2Ccoins%29%29\"\r\n" );
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document.write( "     0.05x + 0.25y = 3.85\r\n" );
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document.write( "Get rid of decimals by multiplying every term by 100:\r\n" );
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document.write( "          5x + 25y = 385\r\n" );
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document.write( " So we have the system of equations:\r\n" );
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document.write( "          \"system%28x+%2B+y+=+25%2C5x+%2B+25y+=+385%29\".\r\n" );
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document.write( "We solve by substitution.  Solve the first equation for y:\r\n" );
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document.write( "             x + y = 25\r\n" );
document.write( "                 y = 25 - x\r\n" );
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document.write( "Substitute (25 - x) for y in 5x + 25y = 385\r\n" );
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document.write( "   5x + 25(25 - x) = 385\r\n" );
document.write( "    5x + 625 - 25x = 385\r\n" );
document.write( "        -20x + 625 = 385\r\n" );
document.write( "              -20x = -240\r\n" );
document.write( "                 x = 12 = the number of Nickels.\r\n" );
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document.write( "Substitute in y = 25 - x\r\n" );
document.write( "              y = 25 - (12)\r\n" );
document.write( "              y = 13 Quarters.\r\n" );
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document.write( "The number of Quarters is 25-x or 25-12 or 13 Quarters.\r\n" );
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document.write( "Checking:  12 Nickels is $0.60 and 13 Quarters is $3.25\r\n" );
document.write( "            That's 25 coins.\r\n" );
document.write( "            And indeed $0.60 + $3.20 = $3.85\r\n" );
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document.write( "Edwin

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