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July 28, 2014

July 28, 2014

Posted by **Mari** on Thursday, January 19, 2012 at 9:56pm.

~Please provide an explanation as well.

Please and thanks!

- Math. -
**Reiny**, Thursday, January 19, 2012 at 11:28pmcost of CD --- x

cost of DVD -- y

3x + y = 20 ---> y = 20-3x

2x + 2y = 22

x +y = 11

use substitution:

x + (20-3x) = 11

-2x = -9

x = 4.5

then y = 6.5

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