document.write( "Question 254371: A music store is selling compact disks for $11.50 and $7.50. You buy
\n" ); document.write( " 12 disks and spend a total of $110. How many compact disks that cost
\n" ); document.write( " $11.50 did you buy?
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Algebra.Com's Answer #186720 by palanisamy(496)\"\" \"About 
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A music store is selling compact disks for $11.50 and $7.50.
\n" ); document.write( "Let the number of disks of first type bought = x
\n" ); document.write( "and the number of disks of second type bought = y
\n" ); document.write( " Total number of disks x+y = 12 ...(1)
\n" ); document.write( "Total amount 11.50x+7.50y = 110 ...(2)
\n" ); document.write( "(2)*2 => 23x+15y = 220 ...(3)
\n" ); document.write( "(1)*15=> 15x+15y = 180 ...(4)
\n" ); document.write( "(3)-(4)=> 8x = 40
\n" ); document.write( " x = 40/8
\n" ); document.write( " x = 5
\n" ); document.write( "(1) => 5+y = 12
\n" ); document.write( " y = 12-5
\n" ); document.write( " y = 7
\n" ); document.write( "Therefore the number of diks of price $ 11.50 = 5\r
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