Answer :
[tex]lb-pound;\ oz-ounce\\\\1lb=16oz\to1oz=\frac{1}{16}lb\\\\therefore\\\\80oz=80\cdot\frac{1}{16}oz=\frac{80}{16}oz=\boxed{5oz}[/tex]
5 pounds, because 16 ounces goes into 1 pound, so i divide 80 by 16 and got 5
