document.write( "Question 1008107: A library is having a book sale to raise money. Hardcover books cost $4 each and paperback books cost $2 each. A person spends $26 for 8 books. How many hardcover books did she purchase? \n" ); document.write( "

Algebra.Com's Answer #623870 by ikleyn(52786) $\"\"$ $\"About$

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document.write( " x +  y = 8,    (1)\r\n" );
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document.write( "4x + 2y = 26,   (2)\r\n" );
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document.write( "where x and y are the numbers of hardcover and softcover books respectively.\r\n" );
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document.write( "To solve, multiply the equation (1) by 2 (both sides) and then distract it from the equation (2). You will get\r\n" );
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document.write( "4x - 2x = 26 - 16,   or\r\n" );
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document.write( "2x = 10,   or   x = 5 - the number of hardcover books purchased.\r\n" );
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document.write( "Then from the equation (1) you get y = 3.\r\n" );
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document.write( "Check. 4*x + 2*3 = 4*5 + 2*3 = 26. OK.\r\n" );
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