document.write( "Question 1175437: A child is collecting state quarters and new $1 coins. If she has a total of 21 coins, and the number of quarters is 9 more than the number of dollar coins, how many of each type of coin does she have?
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Algebra.Com's Answer #801065 by ikleyn(52775) $\"\"$ $\"About$

You can put this solution on YOUR website!
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document.write( "You can solve it in this way, using one single equation\r\n" );
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document.write( "    D + (D + 9) = 21  coins\r\n" );
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document.write( "        2D      = 21 - 9 = 12\r\n" );
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document.write( "         D               = 12/2 = 6\r\n" );
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document.write( "obtaining the answer  6  one-dollar coins  and  6+9 = 15 quarters.\r\n" );
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document.write( "Or, alternatively, you can write a system of two equations\r\n" );
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document.write( "    Q + D = 21\r\n" );
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document.write( "    Q - D =  9\r\n" );
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document.write( "and then add the equations, obtaining\r\n" );
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document.write( "    2Q = 21 + 9 = 30\r\n" );
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document.write( "     Q          = 30/2 = 15  quarters and  15-9 = 6 one-dollar coins.\r\n" );
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document.write( "You can choose any of these two way - they lead you to the same answer.\r\n" );
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\n" ); document.write( "\n" ); document.write( "To see a million other similar solved problems, look into the lesson\r
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