Abby can buy an 8 pound bag of dog food for $7.40 or a 4 pound bag of the same dog food for $5.38. which is the better buy?

One way to find out which bag is better to buy is to find out how much is 1 pound worth in both situations. So we have to divide the prices of 8 pound bag by 8 and 4 pound bag by 4:

$7.40 ÷ 8 = $0.925 per pound
$5.38 ÷ 4 = $1.345 per pound

1.345 > 0.925, so it's better to buy 8-pound bag

The variables should add up to equal 1

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