A crate containing a puppy weighs 60 pounds. The puppy weighs 40 pounds. How much does the crate alone weigh?
Subtract 40 pounds (the weight of the puppy) from 60 pounds (the weight of the crate).
Converting an additional pound of the crate to ounces makes the subtraction possible.
Do the subtraction:
60 pounds - 40 pounds
= 20 pounds