Store 1: 12 towel rolls for $3.30
Store 2: 15 towel rolls for $3.50
Divide 3.30 by 12 ⇒ 3.3/12 = $0.275 per roll - Store 1
Divide 3.50 by 15 ⇒ 3.5/15 = $0.233 per roll - Store 2
Store 2 has the lower unit price per roll, so [tex] \boxed {Store~2} [/tex] has the better deal.