Answer:
$0.60
Explanation:
If you purchase 6 rolls, you pay $3.60
Each roll is $0.60.
If you purchase 13 individual rolls, you pay
13 x 0.6 = $7.80
But if you purchase the Baker's dozen, you pay only $7.20, so you save $0.60
7.80 - 7.20 = 0.60
Hope this helps! :)