Final answer:
To subtract the given weights, subtract the pounds and the ounces separately. Subtracting the pounds: 12lb - 5lb = 7lb. Subtracting the ounces: 3oz - 7oz = -4oz (borrowing 1 pound and converting it into ounces: 7lb - 1lb = 6lb, -4oz + 16oz = 12oz).
Step-by-step explanation:
To subtract the given weights, we need to subtract the pounds and the ounces separately.
Subtracting the pounds: 12lb - 5lb = 7lb
Subtracting the ounces: 3oz - 7oz = -4oz (Since we cannot have a negative number of ounces, we need to borrow 1 pound from the pounds part and convert it into ounces: 7lb - 1lb = 6lb and adding the borrowed 16 ounces: -4oz + 16oz = 12oz)
Putting the results together, the final weight is 6 lb 12 oz. Therefore, the correct option is D. 6 lb 12 oz.