Question

by 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 ones better 2 buy 

Answer 1

$7.40/8 = $0.925 per pound.
$5.38/4 = $1.345 per pound.
1.345 > 0.925, so it's better to buy the 8 pound bag rather than the 4 pound bag.

Answer 2

You should by the 8 pound bag because it has more for less.