Answer :
1x Container - 0.89c costs $0.89c
12 x Container - 0.89c costs $10.68
But it cost $8.64 so you do
$10.68 - $8.64 = $2.04
So $2.04 is saved per case.
12 x Container - 0.89c costs $10.68
But it cost $8.64 so you do
$10.68 - $8.64 = $2.04
So $2.04 is saved per case.