let x be the cost of a single CD

let y be the cost of a single DVD

then 11x + 12y = 150.62

and    y + 12x = 116.07

all we have do is calculate x and y

we will do this by the process of elimination

multiply the bottom equation by 12

so we have the two equations now looking like this:

11x + 12y = 150.62

12y + 144x = 1392.84

subtract the top from the bottom

that leaves us with:

144x-11x=1392.84 - 150.62

133x = 1242.22

x=9.34

substitute this value of x into either of the two equations at the top to find y:

11(9.34) + 12y = 150.62

12y = 47.88

y=3.99

cost of a CD is $9.34

cost of a DVD is $3.99