Posted by Tory Smith on Saturday, January 15, 2011 at 5:33pm.
The cost of thirteen CDs and seven DVDs is $99.80; and the cost of seven DVDs and twelve CDs is $84.11.

math  helper, Saturday, January 15, 2011 at 5:52pm
want do you need to find?
this problem is not complete

math  Jen, Saturday, January 15, 2011 at 5:55pm
13c+7d=99.8
12c+7d=84.11
Multiply the 2nd equation by 1
13c+7d=99.8
12c7d=84.11
c=
Plug that back into either original equation to solve for d.
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