SOLUTION: Three CD's cost and four DVD's cost $108. Five CD's and three DVD's cost $114. Find the cost of one CD and one DVD.

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Question 737557:
Three CD's cost and four DVD's cost $108. Five CD's and three DVD's cost $114. Find the cost of one CD and one DVD.
Answer by checkley79(3341) About Me  (Show Source):
You can put this solution on YOUR website!
3C+4D=108 MULTIPLY BY 3
5C+3D=114 MULTIPLY BY -4 & ADD
9C+12D=324
-20C-12D=-456
-------------------
-11C=-132
C=-132/-11
C=$12 COST OF 1 CD.
3*12+4D=108
36+4D=108
4D=108-36
4D=72
D=72/4
D=$18 COST OF 1 DVD.
PROOF:
5*12+3*18=114
60+54=114
114=114