Hi!
He has 25% of the bottle left.
Knowing he drank 21 oz. out of a 28 ox. bottle, he has 7 oz. left.
We want to know the answer to: 7 is what percent of 28?
To do this, we simply take 7 and divide it by 28. 7/28 is 1/4, which can be represented by 0.25
0.25 as a percent is 25%.
