Answer:
Therefore, we conclude that William left 90.9% of an ounce of his coffee.
Explanation:
We know that William has a 22 ounce coffee. He drinks 2 ounces. We calculate percentage of ounces William has left of his coffee.
We get 22-2=20 ounce coffee.
We have the following proportion:

Therefore, we conclude that William left 90.9% of an ounce of his coffee.