Question

A store is having a sale on 200 DVD movies. Some of the movies are being sold for $10 and some of them are being sold for $12. If the store made $2200 after selling all 200 DVDs, how many $12 DVDs were sold?

Answer 1

$10x+$12y= $2200
x+y=200
multiple the bottom equation by -10
So you now
$10x+$12y= $2200
-10x-10y=-2000
(the x's cancel out) nad you are left with 2y=200
y=100 so 100 $12 DVD's were sold

Answer 2

thanks!