We can find price of each case and then we can decide
Case-1:
Abby can buy 8-pound bag of dog food for $7.40
so, for 8 pound bag = $7.40
now, we can find price
[tex]p=\frac{7.40}{8}[/tex]
[tex]p=0.925[/tex]
Case-2:
a 4-puond bag of the same dog food for $5.38
So, for 4 pounds = $5.38
now, we can find price
[tex]p=\frac{5.38}{4}[/tex]
[tex]p=1.345[/tex]
So, we can see that cheapest price is $0.925 per pound
so, first case is better
so,
8-pound bag of dog food for $7.40..........Answer