Answer:
Brand A
Step-by-step explanation:
The cost comparison can be done a variety of ways. The most formal of solutions will calculate the cost per bag for the two brands.
<h3>Informal solution</h3>
The cost for 10 bags of Brand B is $3.99/3 = $1.33. The cost for 10 more bags (40 bags instead of 30) of Brand A is $4.59 -3.99 = $0.60. This is less than the $1.33 it would cost to buy 10 more bags of Brand B, so ...
Brand A is the better buy
<h3>Formal solution</h3>
The cost per bag is found by dividing the cost by number of bags:
Brand A: $4.59 / (40 bags) = $0.11475 per bag
Brand B: $3.99 / (30 bags) = $0.133 per bag
13¢ per bag is more than 11¢ per bag, so Brand A is the better buy.