The 12 lb bag for $ 18 is better to buy.
Explanation:
Given,
Choice 1: A 12 lb bag for $ 18.
Choice 2: A 15 lb bag for $ 24.
To find which choice is better.
For choice 1:
12 lb bag cost $ 18
1 lb bag costs = $ 18÷12 = $ 1.5
For choice 2:
15 lb bag cost $ 24
1 lb bag costs = $ 24÷15 = $ 1.6
Hence,
The 12 lb bag for $ 18 is better to buy.