For this case we must find the number of ounces that there are in 12.4 pounds, if we have as data that 16 ounces represent 1 pound, then we can make a rule of three of the form:
16 ounces -----------> 1 pound
x ----------------------> 12.4 pounds
Where "x" represents the number of ounces in 12.4 pounds. So, we have:

So, in 12.4 pounds there are 198.4 ounces
Answer:
198.4 ounces