SOLUTION: Four CDs and three DVDs cost �108, while one DVD and three CDs cost �56. Find the cost of a CD and the cost of a DVD. Let c = cost of a CD d = cost of a DVD.

Question 985202: Four CDs and three DVDs cost �108, while one DVD and three CDs cost �56.
Find the cost of a CD and the cost of a DVD.
Let c = cost of a CD
d = cost of a DVD.
Answer by srinivas.g(540) (Show Source): You can put this solution on YOUR website!
et c = cost of a CD
d = cost of a DVD
Four CDs and three DVDs cost �108
4c+3d =108........(1)
one DVD and three CDs cost �56
3c+d=56...........(2)

Solved by pluggable solver: SOLVE linear system by SUBSTITUTION

Solve:
We'll use substitution. After moving 3*d to the right, we get:
, or . Substitute that
into another equation:
and simplify: So, we know that d=20. Since , c=12.

Answer: .

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