Answer:
88%
Explanation:
You can do this pretty easily because percent is just decimals where the decimal is moved 2 units to the right.
Since the base is 25, and 3 of them are oatmeal, you can multiply by 4/4 to get a base of 100, to make this a lot easier.
3 / 25 = x / 100
3 x 4 = 12
12/100 are oatmeal.
Since you don't want the oatmeal, you subtract 100 by 12 to find the remaining of 88.