Question 160692
That's a good start.
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3c + 2t =72
 c + 3t =52 
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Now, let's multiply both sides of the bottom equation by -3:
 3c + 2t =  72
-3c - 9t =-156 
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Combine both equations:
 3c + 2t =  72
-3c - 9t =-156 
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     -7t = -84
       t = 12 (dividing both sides by -7)
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Using the above, we can plug it into equation 2:
 c + 3t =52 
 c + 3(12) =52 
 c + 36 =52 
  c = 16
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Solution:
tapes: $12
cd: $16