You can figure out by using a ratio, so, 25/100 = ?/33. First, figure out what you can multiply 33 by to get 100, or divide 100 by 33, which is 3.0303030303. You can then divide 25 by 3.0303030303, and get 8.25, and voila, 25% of 33 is 8.25 because you know the ratio of 25/100 = 8.5/33
