Answer
A DVD is 15 dollars.
A CD is 7 dollars.
Work Step by Step
Let $D$ be the price of a DVD.
Let $C$ be the price of a CD.
Two DVDs and five CDs for 65 dollars.
$2D+5C=65$
Four DVDs and three CDs for 81 dollars.
$4D+3C=81$
$2D+5C=65$
$4D+3C=81$
Multiply first equation by -2.
$-4D-10C=-130$
$4D+3C=81$
Add both equations.
$-7C=-49$
$C=7$
Solve for $D$
$2D+5C=65$
$2D+5(7)=65$
$2D+35=65$
$2D=30$
$D=15$
A DVD is 15 dollars.
A CD is 7 dollars.
