Respuesta :

(1 lb 6 oz) + (1 lb 4 oz) + (12 oz) = 2 lb 22 oz.

16 oz = 1 lb, so the quantity (1 lb - 16 oz) evaluates to zero. This lets us rewrite the sum as (2 lb + 22 oz) +(1 lb - 16oz) = 
   3 lb 6 oz